Added Plesk-Driver to Password-Plugin

This Driver allows to change Passwords via Plesk RPC-API
fixed typos and added section in README
wrong type returned for gif
rotate image with GD if exit rotation data present
Allow browsers internal spellchecker to work

Fix a regression introduced at 731d190 that prevents in-browser spellchecker from working.
The new TinyMCE4 option is "browser_spellcheck", before it was "gecko_spellcheck".

Related ticket: http://trac.roundcube.net/ticket/1485060
Remove $config['default_folders'] from config tips

Remove $config['default_folders'] from config tips as this option was removed on commit dc0b500.
Related ticket: http://trac.roundcube.net/ticket/1489737
Set edited folder name to client environment
changes suggested by aleks
Fix unintentionally hidden contacts search box in compose screen
Allow to search for LDAP groups with 'group_filter' enabled
Get rid of "Properties" fieldset in folder form
Merge pull request #211 from bbraybrook/gd_rotate_thumb

Fix incorrect thumbnail rotation with GD and exif orientation data (#1490029)
Cleanup after PR merge, updated changelog
Allow focussing treelist item checkboxes with tab and normal list navigation with cursor keys (#1489648)
Extend rcmail::url() to produce absolute and fully qualified URLs
Place folder namespace selector above search box. Adjust height after box is visible and real heights can be computed
Don't read attachment contents from cache when downloading. Cache might have line endings converted
Support contacts import in GMail CSV format
Merge branch 'master' of github.com:roundcube/roundcubemail
Fixed failing test