NCBC-733: use given transcoder in Set operation

Motivation
----------
Contrary to the Insert operation, Upsert doesn't seem to take the given
serialization settings into account. For example, when configuring the
serializer to use PascalCase, upsert still stores camelCase.

Modifications
-------------
Made every call to the Set operator (upsert) take a ITypeTranscoder in,
as is the case with Add (insert).
Removed the constructor on Set that didn't offer to pass a transcoder.

Modified every tests that used the Set operator.

Added a test in CouchbaseBucketTests that ensure the custom setting is
picked up in Upsert.

Fixed a typo that would get the _transcoder attribute never initialized
in ConfigContextBase.

Result
------
Tests pass, Upsert operation now correctly takes SerializationSettings
into account.

Note: GetSetPerformanceTests.Test_Timed_Execution was also previously
failing. Tracked in NCBC-751.

Change-Id: I08c344ce7c7654c6e55cf5ce22fcf12183cb1268

Conflicts:
	Src/Couchbase.Tests/IO/Operations/GetSetPerformanceTests.cs
Change-Id: If3fe7c4985733951147ab974e179b1cb60448e5c
Reviewed-on: http://review.couchbase.org/44620
Reviewed-by: Jeffry Morris <jeffrymorris@gmail.com>
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>