Spruce up submission update email.
fix #815 use redcarpet (markdown) instead of redcloth (textile)
replace RedCloth with redcarpet
replace RedCloth with redcarpet
try removing the ruby gems restriction
Merge branch 'refs/heads/master' into ticker_redcarpet

* refs/heads/master:
  try removing the ruby gems restriction
add back postgres to gem lock file
Merge pull request #818 from concerto/ticker_redcarpet

use redcarpet (markdown) instead of redcloth (textile)
add Travis badge
fix #820 null style causes split error on position's getContentStyles
Merge pull request #821 from concerto/position_without_styles_fix

fix #820 null style causes split error on position's getContentStyles
Per #817, brought duration validations in line with ConcertoConfigs
Reverting eb79f847d95140f20bf7d336608bafa093cbab20 and leaving duration up to the moderator
Hide field_config key selector when there are no keys to pick.  Close #823.
Clean up the forms for #823.
Improve error handling for 404s, close #825.
Handle missing content previews better, close #826, #827.
Per #817, make sure the recipient and the originator of an action aren't the same entity
Per #817, make the submission update emails more useful
add thead/tbody for #823