Change GC daemon to optionally use paginated 2I queries

Change the GC daemone to optionally use paginated 2I queries to avoid system
stress and timeouts when the amount of garbage to be collected is large. The
`paginated_indexes` boolean option is used to enable the use of paginated
queries and may be used when the version of Riak being used is >= 1.4.0. The
default for the option is false. There is also an option, `gc_batch_size`, to
configure the amount of results that should be requested by the 2I query at
one time. The default for this option is 1000.