Example: "User joined project Namespace / Project" rather than "User joined project at Namespace / Project"

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Update the `#first_line_in_markdown` method so that the first line of
parsed text is displayed more reliably, and the continuation indicators
("...") are displayed in all cases where the note is truncated.

Also add Rspec tests for `EventsHelper#event_note`.

Notes on the dashboard views are truncated to 150 characters; this
change ensures that when a link's text is truncated it still points to
the correct URL.

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

This fixes #305.

The event helper is used extensively within the dashboard atom feed, so by
fixing this, we fixed #303.

This fixes #304 since it was linking back to the dashboard feed
only as a result of it being given no URL at all for notes.

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

* call set_iid before validation
* make rake task pass event if objects are invalid
* show iid in comment event at dashboard