Fix test logic
Removed unused constructor in InsertRequest

JAVA-1419
[JAVA-1410] Updating Javadoc for legacy public API. Added Javadoc for missing classes and methods, and for the com.mongodb package, but also updated content and formatting for some of the key existing functionality.
[JAVA-1410] Javadoc for Legacy API. Added missing javadoc, tidied some of the existing (particularly capitalisation), renamed some parameters for ease of reading.  Also removed the UnknownHostException that is declared on a lot of the Mongo methods as this is never actually thrown.
[JAVA-1410] Fixes from Ross's suggestions: updated docs for createCollection, removed a duplicate test for createCollection and added a new test to show what happens if the collection already exists.
[JAVA-1410] Fixes from Ross's suggestions: tidying DBCursor code.