Pull common queries out from a base class

The base class was causing the dispose to not fire correctly inside both
the consumer and producer.  I have moved the common queries into a class
called MetadataQueries and provided an interface for it.  Both the
consumer and producer now simply implement this interface to expose the
two methods.  Not sure if this is the best way to remove the base class
dependency which I didn't like in the first place.  Test are passing now
for consumer and producer.
Add nuspec to kafka-net project

AppVeyor requires nuspec to be in the root of the project to create a
nuget package for.
Change nuspec to match version variable from appveyor
Update location of build files for nuspec

Figuring out how appveyor works
tests has some multi-threading issue.
tests has some multi-threading issue and hanging there.
backup
dispose consumer to prevent previous tests blocking later tests and cause it fail
dispose consumers to release resource
merge with master
OffsetFetchRequest works, with tests passed. Some indeterministic errors occur in other tests, but it's unrelated
clean up
Merge pull request #1 from aNutForAJarOfTuna/OffsetFetchRequest

Tests passed.