Replaces PEAR_WORKING_DIR with git_dir. (Fixes #32)
We are no longer exporting variables in git-pear!
Pear exits with info if called in a dir without .git
Moved git_dir assignment to where PEAR_WORKING_DIR used to be exported
[#38] Uninstall is now quit
Merge pull request #40 from salarkhan/no-export

Tested on test-branch looks cool.  Merggggg (pronounced like surge but a bit more french and pretentious like Serge)