[JAVA-1391/2/3] Fixed Javadoc so it builds under Java 8.
Reducing the memory needed by the build in the hope that travis will stop killing our jobs.
Created a check in the build to let us turn off running @Slow tests.  Using this setting for Travis so that we don't use too much memory / time for the build that we run there. Applied the @Slow annotation to any tests in core or driver that take longer than 0.5 seconds locally, or that use an unusually high amount of memory.
[JAVA-1391] Javadoc for com.mongodb.codecs package (added missing Javadoc). Also some tiny tidy ups, like making methods private and removing @SuppressWarnings where possible.
Merge branch '3.0.x' into crud-1

Conflicts:
	driver-core/src/test/functional/com/mongodb/operation/ReplaceOperationSpecification.groovy
	driver-core/src/test/functional/com/mongodb/protocol/WriteCommandProtocolSpecification.groovy
Fix MixedBulkWriteOperationAsyncSpecification

JAVA-1215