Merge pull request #282 from shaitan/recovery

Recovery: fixed failes stats in deep_merge.
v2.24.14.31
IDS: Added config flag which turns on saving and recovering ids from elliptics cluster.
Filters: Fixed filters::all filter

Previous implementation was equal to filters::positive, which is
a bug
Indexes: Implemented session::remove_index

This is first non-suboptimal draft of remove index's implementation.
More perfomance issues must be fixed for production-ready state.
Merge pull request #284 from shaitan/master

IDS: Added config flag which turns on saving and recovering ids from elliptics cluster.
ids: get rid of unneeded function argument
Merge pull request #285 from euroelessar/master

Implemented session::remove_index