Fixed performance when search packages.

In old version bower getting all items from json and looked for fitting package. 
Now use api: `http://bower.herokuapp.com/packages/search/<package>`

Profiler results:
before:
`./bowerphp search sizzle --profile`
`Memory usage: 4.7MB (peak: 58.21MB), time: 29.41s`

after:
`./bowerphp search sizzle --profile`
`Memory usage: 4.67MB (peak: 4.77MB), time: 1.01s`