jquery.makeCollapsible: Tests for collapse and expand text

Provided via data- attributes (data-collapsetext, data-expandtext)
and via options (options.collapseText, options.expandText).

Change-Id: I8922b80ee9aff149a56c9ca44edc247033fc6d6a
jquery.makeCollapsible: Consistency in test names

Mention which part of the code is being tested in parentheses in test
names. Some actions can be triggered inmore than one way or in more
than one context: this gives a clearer image of what has tests already
and what hasn't.

Change-Id: I48dcf831f6a622f08061b29ca90fb0614e4cbab6
Merge changes I48dcf831,I8922b80e

* changes:
  jquery.makeCollapsible: Consistency in test names
  jquery.makeCollapsible: Tests for collapse and expand text