added configOptions to bower.install

allows the use of additional config options that are available in bower:

    force: { type: Boolean, shorthand: 'f' },
    offline: { type: Boolean, shorthand: 'o' },
    verbose: { type: Boolean, shorthand: 'V' },
    quiet: { type: Boolean, shorthand: 'q' },
    loglevel: { type: String, shorthand: 'l' },
    json: { type: Boolean, shorthand: 'j' },
    silent: { type: Boolean, shorthand: 's' }