GEOMESA-387 Handles multiple clients creating new schema

* Logs TableExistsExceptions rather than allowing them to bubble up
GEOMESA-384 removing commons-net 2.2 in favor of 3.3

fixing comments in pom
excluding maven scm jars
removing jxpath
fixing version of objenesis
GEOMESA-389 Refactor SimpleFeatureEncoder

Separated encoder trait from decoder trait