Mms: Enable SoftBank emoji encoding

This adds an option to enable SoftBank emoji encoding when inserting
emoji into SMS/MMS message.

There is nothing wrong with the default Unicode emoji encoding other
than the fact that most Japanese carriers does not support it as they
have their own coding conversion tables. The option toggles to SoftBank
encoding, the decoding both Unicode and SoftBank-codeed emoji is
alredy working correctly (both code tables are already part of the
src/com/android/mms/util/EmojiParser.java). Unicode encoding will
stay the default.

port from http://review.cyanogenmod.org/#/c/34500/

Change-Id: I494cb6d2ce022e0f00a46e38b84384f1e80b23e4
Signed-off-by: rdgate <rdgate@gmail.com>
Custom user-agent option

port from https://github.com/CyanogenMod/android_packages_apps_Mms/commit/afac2716ff7c43234fe1ba4a0247a25707c3a6c1
Custom user-agent is necessary for MMS access on the Softbank mobile network in Japan.

PS2: rebase
PA3: rebase

Change-Id: Ia3743360cb4660babbfa3311de016ee3b888a858
Signed-off-by: rdgate <rdgate@gmail.com>
Merge changes I494cb6d2,Ia3743360 into jb-mr1

* changes:
Custom user-agent option.
Mms: Enable SoftBank emoji encoding.

Change-Id: Icb5c165ecca57fa9c8bcba676bb97b631a3ee11b