Added manager. Must add tests to confirm we can use that for searches.
Must also add examples for this.
When mapping, it is now possible to return the same items as those used
for the search (e.g. `Article.bungiesearch.search("match",
_all="Title").fields('pk').only('__fields')[0]`). Warning: yet untested.
Added tests to check result responses and automatic mapping. Corrected a
few related bugs at the same time.
Merge pull request #7 from Sparrho/issue-5

Settings only read once. Added manager. Corrected iterator. Added tests.