Supports iOS7 - iOS8
For iOS9, try iMAllFile
iMAllFile : let you send any type of file from iMessage with a simple file browser which let you browse the hole filesystem and choose any file to send.
How it works:
-- after enabling it from settings, you wil see a new share button on top right of the navigation bar, which will open the filesystem browser.
-- and after that you will see an popup menu which have an iMAllFile option click on it and it will let you send the chosen file to your recipient.
Note: if you have not picked a recipient or existing thred, it may crash while pushing the button
Best wishes
@iMokhles