Changes for publisher field

Do not store against CKAN maintainer field, we want it to be loosely
coupled to the internal model, so an extra is better for this.
Improvements in the converter and the xml parser.
Adds a gitignore to the repository
Merge pull request #8 from datagovuk/gitignore

Adds a gitignore to the repository
Fix BaseController import for CKAN 2.0.x
Merge branch 'master' of github.com:okfn/ckanext-dcat