fix exceptions on PutCompareExchangeValueOperation

This commit adds the support for encoding the key property of
PutCompareExchangeValueOperation, thus allowing it to be used
with special characters which would break the URL otherwise.
This function is already used on all other operations, like
GetCompareExchange so it's safe to use in here too.

Author: cabelitos

src/Documents/Operations/CompareExchange/PutCompareExchangeValueOperation.ts

@@ -72,7 +72,7 @@ export class PutCompareExchangeValueCommand<T> extends RavenCommand<CompareExcha
     }
 
     public createRequest(node: ServerNode): HttpRequestParameters {
-        const uri = node.url + "/databases/" + node.database + "/cmpxchg?key=" + this._key + "&index=" + this._index;
+        const uri = node.url + "/databases/" + node.database + "/cmpxchg?key=" + encodeURIComponent(this._key) + "&index=" + this._index;
 
         const tuple = {};
         tuple["Object"] = TypeUtil.isPrimitive(this._value)