Revert "Mms: Remove text/plain for ACTION_SEND"

This reverts commit 33665adcb603be97ea1eaeba29ecfe686f709553

Change-Id: I8818d8f27013b2ed87095b3d8049684b2cdb96a4
Merge "Revert "Mms: Remove text/plain for ACTION_SEND"" into cm-10.1