Drop xforms as a requirement

mUzima core module in OpenMRS requires XForms to support XML forms. It is most likely that XML forms are not used by many mUzima users, if any. This ticket therefore involves dropping XForms requirement that currently happens as a prerequisite for mUzima core to be installed.

The module should be updated to not require XForms during installation, and to check whether XForms is installed at runtime and disable XForms-dependent functionality if XForms is not installed.