Gravatar documentation first steps
Work in progress
Corrections
Last example
Fix for tabulations

Now there are 4 spaces for tab
Indents fix
One more fix for indent
Corrected about passing null to secure setting
Merge pull request #1218 from god107/feature/GravatarHelper

Gravatar Helper doc
[#1218] Edits to new Gravatar page

- Edited for grammar and consistency.
- Corrected a few examples; you do not need to call `->getImgTag()` when `echo`'ing, as the helper
  implements `__toString()`.
Merge branch 'hotfix/1218' into develop

Close #1218