Remove quoted text (and attribution lines) from group posts

[Jim Tittsler]

It would be good to remove email quoted text from group posts.

Attribution lines should also be removed. Formats include:

• On Jul 28, 2015, at 4:35 PM, "User Name" [e-mail] wrote:
• On 2015-07-28, 5:22 PM, "Partner Engagement Working Group on behalf of "User Name" [e-mail] on behalf of [e-mail] wrote:

[Jim Tittsler]

groups: remove common signature blocks and quoting

Fixes #1, and partially addresses issue #2. (Quoting solution currently assumes the user does top posting with a standard attribution line.)

→ <<cset 006517fd52b2>>