These tests would check if the "This project is empty" banner would
contain SSH clone URLs. Oddly enough this should have never passed (as
far as I can tell) as SSH clone URLs in this banner are _only_ displayed
if the current user has at least 1 SSH key attached. Since the tests
never seem to create any they never should have passed, yet somehow they
did. To solve this the Spinach tests in question now ensure at least 1
SSH key is present.

These three tests were essentially checking that adding a note to
something updated its `noteable`'s `updated_at` attribute.

This is well-tested Rails behavior and we shouldn't feel the need to
write an integration test to verify it. At most we should be ensuring
that the association definition adds the `touch: true` option, which we
now do in Note's unit test.

1. We now display the index of the current issuable among all its project's
issuables, of the same type and with the same state.
2. Also, refactored a bit the Issuable helpers into a new IssuablesHelper
module.
3. Added acceptance specs for the sidebar counter.

This also increases capybara timeout to 15 seconds (note polling
interval). Capybara will look for new note for this period of time.