Generate KeyboardLabelsSet from donottranslate-more-keys.xml

This change introduces makelabel tool that reads all languages'
donottranslate-more-keys and generate KeyboardLabelsSet.java source
file. The makelabel command must be invoked prior to compile LatinIME.

Change-Id: I7515c7919c535e30f9c80a37bdc831d0f682cd43