Dockerimage: add phantomjs
Dockerimage: add phantomjs

Add the phantomjs to the Portus Docker image. Needless to say this image
is used for testing and development purposes, it's not meant for
production usage. Hence it makes sense to have all the tools actually
needed at development time.

Signed-off-by: Flavio Castelli <d1035a58d87d0b7918844ad2fd699273faf2f5d5@suse.com>

jloehel/Portus,SUSE/Portus,angry-tony/Portus-20170827,SUSE/Portus,krishnak9/Portus,vpereira/Portus,krishnak9/Portus,krishnak9/Portus,SUSE/Portus,krishnak9/Portus,jloehel/Portus,jloehel/Portus,mssola/Portus,vpereira/Portus,mssola/Portus,vpereira/Portus,angry-tony/Portus-20170827,mssola/Portus,mssola/Portus,SUSE/Portus,angry-tony/Portus-20170827,angry-tony/Portus-20170827