Initial base for the new, experimental schema
Fixed bunch of bugs caused by changed Skill attributes

Moreover, Skills that are referenced by only a single CompetenceNode
are destroyed when that particular CompetenceNode is destroyed.
Added to HABTM scoped_courses and competences associations to Skill
Fixed 'skillable' references in Competence and Skill
Fixed a lot of Skill.skillable references

Instead, fixed them to point to Skill.competence_nodes. The code
cannot be guaranteed to work correctly with the changes, since there
are no tests to confirm this and a lot of the code assumes Skills
only have one 'skillable'.
Fixed a bug caused by illegal syntax
Fix AuthenticatedTestHelper inclusion in test_helper.b

The test couldn't be run since the AuthenticatedTestHelper module
could not be found.
Fixed fixtures that were failing already existing tests
Added Backtrace filtering to Test::Unit tests

The Test::Unit tests use MiniTest.filter_backtrace method to filter
backtraces. The MinitestBacktraceFilter module included in the commit
wraps that method inside another method which adds
Rails.backtrace_cleaner filtering.
Added shoulda gem as a dependency
Added factory_girl gem as a dependency
Initial (Skill) factory for factory_girl
Improvements to FactoryGirl factories
Added 'belongs_to :curriculum' to CompetenceNode

Now both ScopedCourse and Competence belong to a certain Curriculum.
Fixes to Skill#dfs to mirror functionality before schema change
Added an incomplete test for Skill using Test::Unit with shoulda-context
Change Skill 'HABTM' CompetenceNodes association to 'belongs_to'
Added migration for Skill association changes
Adapted code to use the singular Skill.competence_node association
Fixed a couple of scopedcourse.code references to use scopedcourse.course_code