implement optional '--all' in the abandon command
implement optional '--all' in the abandon command

when you want to delete all local branches, you should be find
all branches' name, and type them behind 'repo abandon' command.

Usage:
    repo abandon --all [<project>...]

Change-Id: I4d391f37fb9d89b8095488c585468eafc1a35f31

mer-tools/git-repo,nuclearmistake/repo,GerritCodeReview/git-repo,codetutil/git-repo,qioixiy/git-repo,TheQtCompany/git-repo,TheQtCompany/git-repo,nuclearmistake/repo,gabbayo/git-repo,lipro-yocto/git-repo,codetutil/git-repo,dodocat/git-repo,lewixliu/git-repo,couchbasedeps/git-repo,qioixiy/git-repo,frogbywyplay/git-repo,wavecomp/git-repo,dodocat/git-repo,frogbywyplay/git-repo,aosp-mirror/tools_repo,aosp-mirror/tools_repo,chenzilin/git-repo,lewixliu/git-repo,lipro-yocto/git-repo,wavecomp/git-repo,gabbayo/git-repo,couchbasedeps/git-repo,chenzilin/git-repo,GerritCodeReview/git-repo,mer-tools/git-repo