Adding ability to turn off subject encoding. Useful for emailing to SMS. 2nd try.

This gives you the ability to turn off subject encoding. This is important if you are emailing to SMS portals. (For example, `5551234567@vtext.com` will mail a text message to a verizon customer).

The problem is that many SMS portals do not handle encoded subjects. See http://kb.paessler.com/en/topic/46873-why-do-sms-notifications-have-a-subject-like-subj:-utf-8-b-z29iymxlzglnb29r
for an example of the kinds of problems that UTF-8 encoded subjects can cause these portals. The problems still exist today. 

So, if you know you are emailing a text message, you can use this new ability to avoid the garbage that shows up in the text message. Its not mail standard, but its necessary.