uses deletion strategy for js specs

truncation seems to cause race conditions
updates database_cleaner
Builing up export options meta in wp controller.
Using labels for export formats like in style guide.
Export xls with description label and moved export icon in menu.
Make the toggleable multi-select behave more intuitively
Add styles to export options

- added styles to export options
- added export icon to the action-menu in the toolbar
Locales for export options.
Manage sorting in column menu, react to switching the column context…


… while the menu’s still opened
Merge pull request #1434 from opf/feature/avoid_rspec_capybara_race_conditions

alters database cleaning for rspec to avoid race conditions
Merge pull request #1465 from opf/feature/fix-toggleable-multiselect-8744

Make the toggleable multi-select behave more intuitively
Merge pull request #1466 from opf/feature/export-modal-options-8229

Feature/export modal options 8229
Merge branch 'dev' into feature/client-side-routing-serialize-query

Signed-off-by: Alex Coles <alex@alexbcoles.com>

Conflicts:
	public/templates/work_packages.html
Fix ProjectsController test, broken in 5f3b3be6

Signed-off-by: Alex Coles <alex@alexbcoles.com>