Revert "add using ExpandString"

This commit is reportedly causing compilation issues against ZNC 1.0.

This reverts commit fa464696628b1db9168aa446b555c2c2699268a6.
Add correct forms for using ExpandString in highlight checks

This adds the feature intended for revision fa46469, but using the format
found in the core ZNC perform module.  This patch is verified to compile
against ZNC 1.0.
Add string replacement to message title and content to match url
Fix #25: add support for custom urls using get requests
Use message_uri for URL service rather than target
Changed from <nick> to [nick] in OnChanMsg

Boxcar and other apps delete strings inside <> like IRC nicks, so changed to [nick] from <nick>
Merge pull request #29 from danparsons/master

Changed from <nick> to [nick] in OnChanMsg