Enable symbol and source for the NuGet package

[asbjornu]

I've had to disable the Include sources and symbols checkbox in TeamCity due to a bug in NuGet that causes the build to blow up with the following exception:

[04:31:23][push] Failed to process request. 'Package submission failed: Source file d:\BuildAgent-01\work\b2f932b5a0190733\SharpRaven\Data\JsonPacket.cs not found in package. Source file is declared in SharpRaven.pdb. . See http://www.symbolsource.org/Public/Home/Help for possible reasons. Fiddler may help diagnosing this error if your client discards attached detailed information.'. 
[04:31:23][push] The remote server returned an error: (506) Package submission failed: Source file d:\BuildAgent-01\work\b2f932b5a0190733\SharpRaven\Data\JsonPacket.cs not found in package. Source file is declared in SharpRaven.pdb. . See http://www.symbolsource.org/Public/Home/Help for possible reasons. Fiddler may help diagnosing this error if your client discards attached detailed information...
[04:31:23][push] Process exited with code 1

It would be neat if we could circumvent this bug so we could publish SharpRaven's symbols and source code to SymbolSource.

[asbjornu]

The problem might be fixed in NuGet now, but has been shifted to the AssemblyInfo file that GitVersionTask automatically generates, as explained in GitTools/GitVersion#146.

[asbjornu]

Looks like this has been fixed and SharpRaven v1.5.1+ includes debug symbols.