Fixes #1270 sequrity question

Fixes error text for sequrity question not wrapping.
fix: Warning time error, refs #1283

* warnings.php
  * expires_period was accessed as numeric value, but is a string
* inc/datahandlers/warnings.php
  * improved handling of expiry for custom warning reasons
* inc/languages/english/datahandler_warnings.lang.php
  * added error message for invalid expires_period
Merge pull request #1285 from Nik101010/fix-1283-feature

fix: Warning time error (#1283)
Merge pull request #1280 from avril-gh/Fixes-#1270-sequrity-question-error-not-wrapping

Fixes #1270 sequrity question