Delegate wrapping functions to frameworks and extend interface to ensure that they pick up the responsibility
Restore wrapping functionality for Twitter Bootstrap 2, with slight tweak - unnecessary space before append class has been removed
Wrapping functionality for Nude. No longer inherits Twitter Bootsrap markup, so more nude than before. Still reflect the Bootstrap stucture slightly, so not as agnostic as nude could be.
Crude implementation of wrapping for Foundation 3 and 4. Necessary classes are hard-coded, but they and the structure are now Foundation and not Bootstrap, so it works.
Merge branch 'agnostic' into bootstrap3
Appending and prepending to fields for Bootstrap3

Reverts to extending from framework rather than Bootstrap2 to avoid
inheritance and typing issues. Adds support for appending and prepending
and so is dependent on earlier pull-request #177. Tests to follow.