add efficient filesystem handling for guard
Revert "add efficient filesystem handling for guard"

This reverts commit 6ba615c5866021a30d6b2c50ae33044b180dd14b.
Merge branch 'official'
Merge branch 'official'
add platforms option with unicorn gem, because unicorn can't install in windows
add devise_invitable gem.
add devise invitable table for user.
add devise invitation view.
user apply invitations.
invite user.
add invite reason to users.
fixed rspec error.
change invitation form style.
user can upgrade to create event.
send invited email.
add directly registrtion feature test.
Merge pull request #264 from ywjno/master

add platforms option with unicorn gem
Merge pull request #265 from doitian/switch-back-to-html-pipeline

use html-pipeline since dependencies on charlock has been removed
add exception notification gem. close #248
merge.