Added Billing API methods:
* POST: purchases
* GET: purchases/{id}
* GET: users/current/products
* POST: purchases/{id}/refund

Added configuration for billing api endpoint
Work in progress support for GET:search
Support for GET:search
CRLF setting causing diff issues on Mac
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use DEFAULT_THREADS instead of hardcoded 4
Various SDK changes for the Mac client to work

-changed default threads to 4
-added back the IsFailed property and logic to the
FileDownloadProgressChangedEventArgs class
-manually set the HttpEncoder because of MonoMac bug
Trouble with Nuget on Mac - added references manually
enable threadcount tweaking
rev TV to fix mono segmentation fault issue
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Merge branch 'vertigo-mac' of github.com:basespace/basespace-csharp-sdk into vertigo-mac
misc
it finally builds
hrefappsessionchild for multilaunch create app result
Added AppSessionRoot property to AppSession
removed hrefappsessionchild
Sujit: Moving over the changes from "features/search" branch and fix for download progress event not having the correct fileId
Sujit: might have to undo this commit later on..
Sujit: removed unwanted references