Added missing schema.rb changes from last migrations
Initial 'edit_prereqs' view for Competences
Changed skill prerequirement editor to filter current node from results

Thus, the skills can no longer be set as prerequirement to themselves.
CurriculumsController#search_skills now covers both CompetenceNodes
Renamed competenceSkillEditor as skillPrerequirementEditor
Added underscore.js
Fixed skill strict and supporting prereq assocations

The attribute 'requirement' was not being assigned properly when
Skills were added through the assocations. This commit fixes that.
Added 'requirement' attribute validation to SkillPrereq
Modified skillPrerequirementEditor to always show the current prereqs
Added skill loading cues to view (by fading opacity)

In addition, fixed add_prereq and remove_prereq bug, where the
HTTP requests would fail because JSON response was expected, but
the HTTP API did not return JSON.
Added state rollback to addPrereq and removePrereq in skill prereq edit

The editor now rolls back the shown state if the actions fail.
Changed skillPrereqEditor prereqType to use a computed observable
CoffeeScript style improvements

Removed unnecessary parentheses from function calls.
skillPrereqEditor: clickSelectTarget improvement

clickSelectTarget now checks if any changes are actually needed.
Fixed memory leak in skillPrerequirementEditor.js.coffee
Added placeholder text to search box in skillPrereqEditor
Fixex a bug in skillPrerequirementEditor

Removal and addition of prerequirement skills were not updated
correctly in the results list.
Changed skillPrereqEditor results listing

The results list now shows all current prerequirements when there
are no search terms and when there are search terms, only search
results are shown.
Increased skillPrereqEditor search box width
Enable competence editing in the UI