Basic Gemfile

Signed-off-by: Stephen Celis <stephen@stephencelis.com>
Support arbitrary shell commands to fetch ghi.token

This allows people to, e.g., use the OS X keychain (or platform
alternative) to store tokens.

E.g., to store a newly-generated token in the keychain:

  $ security add-internet-password -a $(git config github.user) \
                                   -s github.com                \
                                   -l "ghi token"               \
                                   -w $(git config ghi.token)

Test it out:

  $ security find-internet-password -a $(git config github.user) \
                                    -s github.com                \
                                    -w

Use it (assuming the above is still the previous line of your terminal
session):

  $ git config --global ghi.token "\!$(echo !!)"

Signed-off-by: Stephen Celis <stephen@stephencelis.com>
Store token on OS keychain

Also provide security information to users not on OS X.

Closes #89, #145.

Signed-off-by: Stephen Celis <stephen@stephencelis.com>
Bump version to 0.9.2

Signed-off-by: Stephen Celis <stephen@stephencelis.com>