Don't add .gitignore file at init time.
Don't add .gitignore file at init time.

Not only do we not need the file at that point, we
were also use 'w' to open it which would blow away
any existing .gitignore file.  Just create it when
necessary, and use 'a' for that (in add_cb())

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@irobot.com>

manuelnaranjo/git-got,jake4679/git-got