Add pull_request source and kind
Fixed bug

- [Fixed] giti#branch#github_list_all()
  - Error occur given branch_name contains '/'
Improve pull_request source

- Append feature
  - Inputing issue number
  - Creating a new pull-request with vim
Fixed some behavior
add branch_recent source
pass --count option to git for-each-ref
Pesky message is houted down!!!
Fixed branch source
Refactor some files
Fix typo
Change behavior of giti#system_with_specifics

It is a little bit annoying that when user execute `:Unite giti/branch`
or so on in non git repository by mistake, user cannot cancel the
process until he/she input a correct git repository.

Now I change the behavior of giti#system_with_specifics thus when user
hit <Esc> (or hit <CR> with empty input), it will cancel the process.
Support 'cancel' source (improve cancel interface)

vim-unite-giti seems to not support cancel the process. It raise
exceptions, show meaning-less candidates, ask same questions again and
again...

I fix these annoying cancel issues. Now if you start giti/XXXX by
mistake and cancel the process, it won't show any exceptions or
unwilling candidates
Merge remote-tracking branch 'chadrien/patch-1' into improve_user_interface
Merge remote-tracking branch 'alpaca-tc/add_pull_request_source' into improve_user_interface

Conflicts:
	autoload/giti.vim