Add Text Area Size preference

This commits add the ability to set the size of the editable
text are for composing messages.

Arbitrary Restrictions:
Min Limit - 2
Max Limit - 15

Change-Id: I20261af0eb7e1daf80327df4cfde6b7efe766b1d

Conflicts:
	res/values/strings.xml
	src/com/android/mms/ui/MessagingPreferenceActivity.java
Mms: Remove text/plain for ACTION_SEND

Always display registered apps for android.intent.action.SEND action, but this is not true.
Actually, it doesn't support that mime/type. Just remove it to avoid unexpected behaviour for
external apps.

See ComposeMessageActivity#addAttachment

Change-Id: I4815a59533dbfc3decfbdbc57bf456ebda3cab7a
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>