Add exacutable mca script and mca.bat to make it runnable without .js extension.

mca.bat was copied from android create.bat
mca was copied from cordova-cli/bin/cordova executable and ionclude the time measurement bits.

Adding bin to package.json makes npm install a symlink in prefix/bin when doint npm install or npm link. This also works well on windows where in addition to the symlink npm creates a .cmd file with proper invocation of the script via node.