Handle additional reply headers
WIP

Got to the signature on test file 2_3. The regex currently looks for
"Sent from my" followed by 1, 2, or three words.
Fix hyphens in paragraphs treated as signatures

A double dash within a paragraph can be used to convey an en dash or an
em dash, so it shouldn't be treated as a signature.
The important change here is that hyphens, and underscores must end the
line, optionally preceded, or followed by spaces.
Handle nil body text

An empty string returns an empty string, might as well have nil return
an empty string. Better than an exception.
wip failing test
Merge remote-tracking branch 'carezone/sandro_fix_body_is_signature' into carezone

Conflicts:
	lib/email_reply_parser.rb
	test/email_reply_parser_test.rb
	test/emails/email_2_2.txt