Merge branch 'dev'
fix bootstrap loading issue
add login in buttons
add admin_menu
add notice message & add new_admin_meetup_path to navbar
install gem simple_form
add form layout
install carrierwave
add uploader to form
add category select to form
ignore uploaded files
add MeetupMember relation
add link to navbar
add layouts
add category bar
add new route meetups#find, add cat_bar at find.html, add meetups#show
add admin_meetup to manage menu, add edit, delete, show events
add event CRUD
add destroy dependency
add events#show