GEOMESA-173 Extract avro features into its own subproject

Moved AvroSimpleFeature into its own subproject.  Implemented
AvroSimpleFeatureFactory to create AvroSimpleFeatures when
using SimpleFeatureBuilder.
GEOMESA-144,GEOMESA-140 Ensure a Temporal Attribute is included in index

GEOMESA-140 Warn users about missing temporal component of index
* This commit adds a warning when a user neglects to properly set SF_PROPERTY_START_TIME in the UserData. Such a mistake is non-fatal, but does impact performance.

GEOMESA-144 Set temporal index variable by default if not selected by user
* This commit will set SF_PROPERTY_START_TIME for the user if a time attribute is present in the SimpleFeatureType, and emit a notification to this effect.
GEOMESA-179 Limit unit test logging

* Limited unit test logging for Travis CI to work. Added flag that can be enabled if developer wants to see output on command line.
GEOMESA-177 Insert waypoints in large Geoserver BBOXs

In order to support GeoServer queries and Spatial4j's IDL handling,
this pr rewrites large BBOXs to have waypoints.
GEOMESA-185 Fix TemporalIndexCheckTest

Use functions to generate the test SFTs to avoid state between test fragments.

Also modify the test codebase to remove triggers of the TemporalIndexCheckTest, and
remove a few new references to geomesa_index_* as an attribute name.
GEOMESA-169 fixing density iterator, restoring expansion of density map

* Fixes a regression in the density iterator.
* Improves the DensityIterator unit tests.