Initial implementation of converting to ContentProviderOperation

ATTENTION: This PR is only an overview, it's not meant to be merged to master yet.

Hello,

This pull-request contains initial, straightforward implementation of converting db-commons' ProviderActions to ContentProviderOperations. The biggest advantage of this mechanism is that we are able to pass ProviderActions as arguments, so receiver can use them both in atomic ContentProvider actions as well as in the applyBatch.

Missing things:
- back refs
- assert query

assert query should be very easy in implementation. I got a couple of ideas to implement back-refs:
- offer an method toCPOBuilder, and return partially done ContentProviderOperationBuilder.
- expose overloaded toContentProviderOperation to receive some data about which back refs need to be used.