Add source and javadoc artifacts to build.
Mark javax.servlet.servlet-api as provided
(thus force the runtime to provide it)

closes #7
Added constructor for OAuthCredentials that allows for setting the userId. Handy for testing
Added private static final long serialVersionUID  to OauthCredentials, to be able to deserialize existing cached credentials.
Merge pull request #9 from chids/make-servlet-dep-provided

Mark javax.servlet.servlet-api as provided
Merge remote-tracking branch 'upstream/master'
Added PoolingHTTPClient