Fix the last 3 functional test failures:
1. increase the timeout for verifying aggregatestats after uploading and then downloading a package
2. fixed the dotnetcuratedsearchtest by comparing strings all using lower cases
3. fixed the downloadusingNuGetcommandline tests by explicitly specifying the outputdirectory for nuget.exe install
Merge pull request #2108 from NuGet/danliu/testfix

Fix the last 3 functional test failures: