[Android] Change the default version to empty in packaging tool.
[Android] Change the default version to empty in packaging tool.

When the manifest.json version value is empty,
the webapp could be packed and installed successfully,
but shouldn't be show version in Apps.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1146

baleboy/crosswalk,axinging/crosswalk,crosswalk-project/crosswalk,huningxin/crosswalk,alex-zhang/crosswalk,jondong/crosswalk,hgl888/crosswalk,xzhan96/crosswalk,weiyirong/crosswalk-1,hgl888/crosswalk,Pluto-tv/crosswalk,stonegithubs/crosswalk,leonhsl/crosswalk,dreamsxin/crosswalk,jpike88/crosswalk,RafuCater/crosswalk,XiaosongWei/crosswalk,heke123/crosswalk,jondwillis/crosswalk,tomatell/crosswalk,PeterWangIntel/crosswalk,fujunwei/crosswalk,RafuCater/crosswalk,jpike88/crosswalk,hgl888/crosswalk-efl,crosswalk-project/crosswalk-efl,DonnaWuDongxia/crosswalk,darktears/crosswalk,Pluto-tv/crosswalk,axinging/crosswalk,chuan9/crosswalk,RafuCater/crosswalk,shaochangbin/crosswalk,tedshroyer/crosswalk,DonnaWuDongxia/crosswalk,Pluto-tv/crosswalk,ZhengXinCN/crosswalk,pk-sam/crosswalk,lincsoon/crosswalk,leonhsl/crosswalk,rakuco/crosswalk,crosswalk-project/crosswalk,crosswalk-project/crosswalk-efl,Pluto-tv/crosswalk,minggangw/crosswalk,dreamsxin/crosswalk,qjia7/crosswalk,jondong/crosswalk,chuan9/crosswalk,siovene/crosswalk,XiaosongWei/crosswalk,pk-sam/crosswalk,fujunwei/crosswalk,tedshroyer/crosswalk,weiyirong/crosswalk-1,rakuco/crosswalk,heke123/crosswalk,qjia7/crosswalk,axinging/crosswalk,weiyirong/crosswalk-1,zliang7/crosswalk,jpike88/crosswalk,chuan9/crosswalk,baleboy/crosswalk,minggangw/crosswalk,stonegithubs/crosswalk,heke123/crosswalk,leonhsl/crosswalk,heke123/crosswalk,jondwillis/crosswalk,marcuspridham/crosswalk,ZhengXinCN/crosswalk,tedshroyer/crosswalk,lincsoon/crosswalk,lincsoon/crosswalk,siovene/crosswalk,leonhsl/crosswalk,mrunalk/crosswalk,crosswalk-project/crosswalk,pk-sam/crosswalk,chinakids/crosswalk,lincsoon/crosswalk,Bysmyyr/crosswalk,xzhan96/crosswalk,hgl888/crosswalk,marcuspridham/crosswalk,baleboy/crosswalk,siovene/crosswalk,hgl888/crosswalk,zliang7/crosswalk,DonnaWuDongxia/crosswalk,darktears/crosswalk,alex-zhang/crosswalk,marcuspridham/crosswalk,rakuco/crosswalk,mrunalk/crosswalk,jpike88/crosswalk,bestwpw/crosswalk,ZhengXinCN/crosswalk,chuan9/crosswalk,amaniak/crosswalk,amaniak/crosswalk,chinakids/crosswalk,stonegithubs/crosswalk,axinging/crosswalk,alex-zhang/crosswalk,myroot/crosswalk,chuan9/crosswalk,amaniak/crosswalk,heke123/crosswalk,bestwpw/crosswalk,huningxin/crosswalk,XiaosongWei/crosswalk,DonnaWuDongxia/crosswalk,shaochangbin/crosswalk,pk-sam/crosswalk,amaniak/crosswalk,pk-sam/crosswalk,fujunwei/crosswalk,tedshroyer/crosswalk,tomatell/crosswalk,TheDirtyCalvinist/spacewalk,TheDirtyCalvinist/spacewalk,xzhan96/crosswalk,Pluto-tv/crosswalk,jondwillis/crosswalk,rakuco/crosswalk,zeropool/crosswalk,hgl888/crosswalk-efl,siovene/crosswalk,alex-zhang/crosswalk,rakuco/crosswalk,baleboy/crosswalk,baleboy/crosswalk,crosswalk-project/crosswalk,Bysmyyr/crosswalk,minggangw/crosswalk,marcuspridham/crosswalk,hgl888/crosswalk-efl,minggangw/crosswalk,huningxin/crosswalk,stonegithubs/crosswalk,heke123/crosswalk,bestwpw/crosswalk,mrunalk/crosswalk,jondong/crosswalk,leonhsl/crosswalk,tedshroyer/crosswalk,zliang7/crosswalk,dreamsxin/crosswalk,XiaosongWei/crosswalk,TheDirtyCalvinist/spacewalk,bestwpw/crosswalk,zeropool/crosswalk,baleboy/crosswalk,tomatell/crosswalk,jondong/crosswalk,weiyirong/crosswalk-1,huningxin/crosswalk,alex-zhang/crosswalk,RafuCater/crosswalk,marcuspridham/crosswalk,zeropool/crosswalk,zeropool/crosswalk,crosswalk-project/crosswalk,marcuspridham/crosswalk,jpike88/crosswalk,ZhengXinCN/crosswalk,jondong/crosswalk,chinakids/crosswalk,stonegithubs/crosswalk,crosswalk-project/crosswalk-efl,TheDirtyCalvinist/spacewalk,tomatell/crosswalk,qjia7/crosswalk,marcuspridham/crosswalk,crosswalk-project/crosswalk,ZhengXinCN/crosswalk,leonhsl/crosswalk,crosswalk-project/crosswalk-efl,tedshroyer/crosswalk,myroot/crosswalk,marcuspridham/crosswalk,jpike88/crosswalk,myroot/crosswalk,bestwpw/crosswalk,dreamsxin/crosswalk,heke123/crosswalk,minggangw/crosswalk,zeropool/crosswalk,fujunwei/crosswalk,fujunwei/crosswalk,darktears/crosswalk,jondong/crosswalk,XiaosongWei/crosswalk,myroot/crosswalk,siovene/crosswalk,Bysmyyr/crosswalk,baleboy/crosswalk,chuan9/crosswalk,qjia7/crosswalk,minggangw/crosswalk,Pluto-tv/crosswalk,RafuCater/crosswalk,leonhsl/crosswalk,zliang7/crosswalk,xzhan96/crosswalk,pk-sam/crosswalk,crosswalk-project/crosswalk-efl,zeropool/crosswalk,Bysmyyr/crosswalk,DonnaWuDongxia/crosswalk,lincsoon/crosswalk,dreamsxin/crosswalk,PeterWangIntel/crosswalk,fujunwei/crosswalk,zliang7/crosswalk,baleboy/crosswalk,jondong/crosswalk,myroot/crosswalk,jondwillis/crosswalk,amaniak/crosswalk,chinakids/crosswalk,amaniak/crosswalk,chinakids/crosswalk,myroot/crosswalk,xzhan96/crosswalk,mrunalk/crosswalk,Bysmyyr/crosswalk,siovene/crosswalk,xzhan96/crosswalk,heke123/crosswalk,darktears/crosswalk,weiyirong/crosswalk-1,jondong/crosswalk,ZhengXinCN/crosswalk,zliang7/crosswalk,hgl888/crosswalk,hgl888/crosswalk,jondwillis/crosswalk,hgl888/crosswalk-efl,crosswalk-project/crosswalk,crosswalk-project/crosswalk-efl,zliang7/crosswalk,xzhan96/crosswalk,Bysmyyr/crosswalk,XiaosongWei/crosswalk,crosswalk-project/crosswalk-efl,Bysmyyr/crosswalk,tomatell/crosswalk,minggangw/crosswalk,dreamsxin/crosswalk,zliang7/crosswalk,bestwpw/crosswalk,lincsoon/crosswalk,hgl888/crosswalk-efl,PeterWangIntel/crosswalk,RafuCater/crosswalk,TheDirtyCalvinist/spacewalk,chuan9/crosswalk,DonnaWuDongxia/crosswalk,PeterWangIntel/crosswalk,chinakids/crosswalk,mrunalk/crosswalk,hgl888/crosswalk-efl,fujunwei/crosswalk,DonnaWuDongxia/crosswalk,darktears/crosswalk,weiyirong/crosswalk-1,rakuco/crosswalk,weiyirong/crosswalk-1,crosswalk-project/crosswalk,huningxin/crosswalk,hgl888/crosswalk,qjia7/crosswalk,ZhengXinCN/crosswalk,darktears/crosswalk,jondwillis/crosswalk,lincsoon/crosswalk,amaniak/crosswalk,xzhan96/crosswalk,lincsoon/crosswalk,huningxin/crosswalk,PeterWangIntel/crosswalk,Pluto-tv/crosswalk,mrunalk/crosswalk,jondwillis/crosswalk,qjia7/crosswalk,darktears/crosswalk,PeterWangIntel/crosswalk,rakuco/crosswalk,pk-sam/crosswalk,alex-zhang/crosswalk,Bysmyyr/crosswalk,zeropool/crosswalk,XiaosongWei/crosswalk,tomatell/crosswalk,PeterWangIntel/crosswalk,minggangw/crosswalk,jpike88/crosswalk,tedshroyer/crosswalk,axinging/crosswalk,shaochangbin/crosswalk,RafuCater/crosswalk,rakuco/crosswalk,siovene/crosswalk,stonegithubs/crosswalk,stonegithubs/crosswalk,shaochangbin/crosswalk,TheDirtyCalvinist/spacewalk,alex-zhang/crosswalk,dreamsxin/crosswalk,bestwpw/crosswalk,axinging/crosswalk,shaochangbin/crosswalk,shaochangbin/crosswalk,tomatell/crosswalk,hgl888/crosswalk-efl,axinging/crosswalk,darktears/crosswalk,hgl888/crosswalk