Rename methods on the curve25519 interface to be a bit more high level.
Cleanup emscripten wrapper class, wrap long lines and such. Also add a
grunt task alias for building the emscripten compiled curve
implementation.
Build with `grunt compile && grunt concat:curve25519` after installing
emscripten.
Enable by either (a) not loading nativeclient.js or (b) setting
`textsecure.NATIVE_CLIENT = false` before loading nativeclient.js.
