Add es_NI locale.

Use the generic Spanish locale as a base.
Update with latest Spanish translations.
Tidy OutgoingMessage macro methods
Remove unused validation
Remove uneeded code / Tidy up
Group class methods before instance methods
Use dot rather than colon for method call
Merge branch 'issues/1778-code-tidy' into rails-3-develop
Restore visited link colour change
Merge branch 'issues/149-wdtk-visited-links' into rails-3-develop
Merge branch 'issues/1863-nicaraguan-locale' into rails-3-develop
Merge branch 'rails-3-develop' of ssh://git.mysociety.org/data/git/public/alaveteli into rails-3-develop
Latest translations from Transifex
Update from Spanish file
Merge branch 'hotfix/0.19.0.4' into rails-3-develop
Update from Spanish file
Remove translation of interpolated variable.
Merge branch 'hotfix/0.19.0.5' into rails-3-develop
Temporarily disallow all robots
Replace existing PublicBodyCategories functionality with db models PublicBodyCategory and PublicBodyHeading