Issue 559: Validating the parameter sizes.

Created three validator methods:
 * isShortString()    -  Max 1.000 chars
 * isMediumString()   -  Max 10.000 chars
 * isLongString()     -  Max 100.000 chars

Added these size validations to all displayName, description and comment bodies.
Removed notEmpty check from isShortString-like validator methods and updated the error messages.
Merge pull request #559 from simong/issue-559-limit-parameter-length

Helenus acting up on large post in a discussion
Merge branch 'master' into issue-558-external-searches