Added secondary indexes

Added msgpack dependency
Merge pull request #41 from euroelessar/master

Added secondary indexes
Added user flags into dnet_io_attr structure - this will be placed into object's metadata.
Added bulk_write overload for data_pointer
Added not_found exception if read zero results
Merge pull request #42 from euroelessar/master

Little changes
Fixed index result assignments
Removed unused function param
Merge remote-tracking branch 'upstream/master' into iterators

Conflicts:
	include/elliptics/packet.h
ext: switch to 64bit flags
debian: whitespace nazzi
debian: sorted build-deps