Scripted Field Searchers bugs

So this is the result of the refactoring that was performed on the integration tests for scripted fields searchers. 

Tests

So I created a new test case ScriptedFieldSearcherAndTemplateSpec which includes tests from (the now removed)
GroupPickerFieldsSpec, TestScriptedFieldsSpec and CustomCannedScriptFieldSpec
and the searcher and template tests from the TestScriptedFields. And some new tests in order to make sure that we test all the available searchers.

Now for each searcher we make sure that we test the following:

• If the script and searcher combination passes the STC successfully and the context is the expected.
• If the result of the script is the expected.
• If the rendered value is the expected
• If we make a JQL search the result is the expected.
• If the json representation of the scripted field is the expected (value and type)

Bugs (discovered from the tests) fixed

So from the above tests few bugs were discovered and fixed.

• For scripted fields with the following searchers projectsearcher, grouppickersearcher, multigrouppickersearcher, multiuserpickersearcher their Json Representation was wrong and in some cases (for group pickers) a call to

  /rest/api/2/issue/${issue.key}

  was resulting to a 500 internal error - if that issue had a group picker scripted field.

• There were also some issues with STC and the configured searchers for fields with the following searchers:
  grouppickersearcher, projectsearcher, versionsercher, _usersearcher_