clean before make - fix clone error
remove git2go tgz after install
Do not download git2go two times
Merge from pr
Merge branch 'make-clean' of https://github.com/tadeuzagallo/gitql into tadeuzagallo-make-clean

Conflicts:
	Makefile
Merge branch 'tadeuzagallo-make-clean' into develop

Conflicts:
	Makefile