Bug 870626 - [MMS] Placeholder is not in input box. Regression. - r=borjasalguero

Closes bocoup/gaia#4
Bug 870536 - [MMS] 'enableSend' method is not working as expected - r=borjasalguero

Closes bocoup/gaia#3
Bug 870124 - [MMS][User Interface] SMS counter display - r=borjasalguero

Closes bocoup/gaia#1

Squashed commit of the following:

commit 014d597a46ca2caeeddf3d29b488b0a657a65f3c
commit ae9ff6df80b79d8c3c6bdf9703afa0e37d72b09d
commit e5bc7d9543cae918650d7801e297218e7a8dcf88
commit 0948a7d688b2cb448c8be3ec259f6486d8255728
commit b3b431a9b83c3db500573fd42e9183ded72666ba
commit 42564701693d0f9c1b5453638c073fb0b74cb1ba
commit bab38215f416299e9bda8c9a49a60f9488aeafcd
commit 552541d755d4ccd187e8245a9dae2a9790a60ce8
commit 062dfc2df6d496c678d5fe60273b3e4e4aae186a
Bug 870618 - [MMS] Live-search panel is not cleaned after sending a SMS.r=borjasalguero

Closes bocoup/gaia#8

(cherry picked from commit 633f391b9946e72fd05bea1b34846c2ded840745)
NPOTB: Unit test fixes from dad2f0f - searchContact is now called with empty to clean up
Bug 869255 - [MMS][User Interface] Attach button fire pick Activity and create Attachment

Implement a button to allow users to choose attachments for MMS messages.