few updates for initial refactoring
merge master
format readme
refactor package gitpkg
go fmt codes
reorganize core package
refactor core package
remove NoGet option
add more tests and support locally update pakckages
refactors and more tests
remove fetch option
new commands: open, list
small refactors
GitPkg: refactor #Fetch and #GetHeadRefName
modify version no.
fix no branch bug
remove debugging codes
fix gitpkg tests and get pak pass go build
New Design for multiple vcs support(undone): refactoring gitpkg actions into pakpkg
reorganize gitpkg