added failing maxscan test.
CSHARP-1000: $maxscan should be spelled as $maxScan

SetMaxScan method added $maxscan option instead of $maxScan option which resulted in that option being ignored by mongod.
CSHARP-1001: Fix certain output formats of JsonWriter.
CSHARP-1005: Fix ReadPreference to provide correct GetHashCode() values.
added missing 1.9.2 release notes file.
code review changes.

Conflicts:
	CSharpDriver.sln
CSHARP-1015: fixed miscellaneous build warnings
added travis and appveyor build files. Updated readme to point at travis and appveyor for build badges.
added flowdock notification to travis.
CSHARP-1013: Initial commit.
CSHARP-1013: Renamed PingTime to RoundTripTime and Ping to Heartbeat.
CSHARP-1013: Added ExponentialWeightedMovingAverage to calculate AverageRoundTripTime.
CSHARP-1013: Support multiple credentials for backward compatibility.
CSHARP-1013: Use WriteConcern.Unacknowledged instead of null to represent unacknowledged write concern.
CSHARP-1013: Added tests for WriteConcern.
CSHARP-1013: Add tests for WValue classes.
CSHARP-1013: Turn on code analysis.
CSHARP-1013: Fixed code analysis warnings (except one still to be analyzed).
CSHARP-1013: Implement serialization of fields of custom exceptions.
CSHARP-1013: Suppress remaining code analysis warning that is a false positive.