Refactors tests

Updates tests for adding a custom value to a filter so that test helper
does not contain assertions.
Fixes #331 - Removes expectation methods from test session_helpers

Moves shared tests to filters_spec instead of session_helpers.
Revert "Fixes #331 - Removes expectation methods from test session_helpers"

This reverts commit 78234582ee2a05f36f21fabfe70fb7a7890eaaa4.
Removes test variables

Removes variables used to separate DOM/input values from test commands,
see
https://github.com/codeforamerica/ohana-web-search/pull/340#issuecomment
-38249544
Fixes syntax error

Test referred to filter variable, which has been removed.
Merge pull request #340 from codeforamerica/test-refactor

Test refactor