Added Outlook boundaries for email parser

Summary:
Outlook wraps a message in 5 dashes on each side when doing replies.
This strips english and danish versions.

Test Plan:
Tried parsing emails with different messages and saw the
expected behaviour with patch applied. Ran arc unit, and saw test
passed.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: 1239