Added git support when package use it as VCS
Added hg support when package use it as VCS
gofmt
Fixed bug: has revision but still force to check(which never changes)
Fixed bug: do not check update again when using tag and commit, not including branch.
change isUnchangablePoint to Pkg's method IsFixed
Added option “—update, -u” for build command
Merge pull request #6 from gpmgo/dev

Dev