Fix typo
Handle non default/utf-8 encoding

Source: https://github.com/ungerik/go-rss/
Keep local copy of go-charset

Source: https://code.google.com/p/go-charset/
Changeset: 29:2679cb91dbf8
Use custom install script for Travis CI

This way, the included go-charset will not be downloaded again.
Also make sure to test only bacaberita module.