Mms: Copy url function

Add a function to copy the url in message body into
clipboard.

Change-Id: I6a3980eb3dc7588d4ea34d5a9c861b0fb2142a5e

Conflicts:
	res/values-zh-rCN/strings.xml
	res/values/strings.xml
	src/com/android/mms/ui/ComposeMessageActivity.java