fixes #2260 Allow ERB in ENC global / class parameters

Adds code to parse the global & class parameters, and adds a setting (default true)
 to disable this if needed. Also has some tests.
fixes #2989 - missing fields in host API output (API v1 and v2)
fixes #3059 - new mail rake task sends foreman reports to each user
fixes #2942 - plugin i18n support

This is first phase of plugins i18n support. More to come later:

 * Extraction from model classes
 * JavaScript extraction and support