Fix for email addresses with plus sign

Gmail email addresses containing plus signs cause problems with
taxonomy terms and taxonomy searching. This fix stores + as .PLUSSIGN.
in the database as a workaround.

Props @dcavins

see 26c22b7fc2

Fixes #96
Readme
Updated iconography

Moved most of the functional icons to a sprite.
Readme update
Minor adjustments to group list css

Fixes problems with display of really long group names and adds a
one-column version of the list for smaller screens.
Readme update
Bump version numbers to 1.0.26
Merge branch '1.0.x'