Provide pop-up lisitng keyboard shortcuts

Pressing the question-mark key (?) produces a pop-up listing the
keyboard shortcuts. Pressing q whilst this window has focus closes it.

I've provided crude translations for the additional ? and q shortcuts,
obtained from Google Translate, but they should be checked by native
speakers.
Ignore Files Change
Mention shortcut to show shortcuts in README
Added Feed Title to infos section

In Link Post types of feed sites the url of the post may refer to a
site different than the feed site.  This modification shows the site
name in the infos section for bookmarks, history, unread_items and
show_item in addition to the url for the post
Update contributors list
Improve mobile version of Green theme
Merge pull-request for the green theme
Merge branch 'master' of git://github.com/jamesscottbrown/miniflux into popup
Improve help popup (pull-request)
Merge branch 'master' of git://github.com/chrislemonier/miniflux into feed-title
Improve the feed title and feed domain display
Remove feed hostname for item display
Add scripts to make archive and tag
Add support for HTML5 video inside feeds
Add the possibility to change the session save path
Change item id everywhere (shorter and use less db space)
Add new allowed tags and new URI scheme
Fix php error
Put count of unread items into translation
Updated translations in locales