Test whether a project name is acceptable for use as an android class.
Returns a promise, fulfilled if the project name is acceptable; rejected
otherwise.
function validateProjectName(project_name) {
    var msg = 'Error validating project name. ';
    //Make sure there's something there
    if (project_name === '') {
        return Q.reject(new CordovaError(msg + 'Project name cannot be empty'));
    }

    //Enforce stupid name error
    if (project_name === 'CordovaActivity') {
        return Q.reject(new CordovaError(msg + 'Project name cannot be CordovaActivity'));
    }

    //Classes in Java don't begin with numbers
    if (/^[0-9]/.test(project_name)) {
        return Q.reject(new CordovaError(msg + 'Project name must not begin with a number'));
    }

    return Q.resolve();
}