GEOMESA-607 enabling caching by default

* Also updating deprecated synchronization in metadata
Merge branch 'f_ds_caching_default' into f_sorted_st_idx

Conflicts:
	geomesa-core/src/test/scala/org/locationtech/geomesa/core/data/AccumuloDataStoreTest.scala
tweaking intra day test
looking up attribute by index vs name in filter