Bump RxSwift version + fix depracated methods warnings

Change-Id: I09f77c6fda83a1d24063fc4e1e4e9110b65e37d9
diff --git a/Ring/Cartfile b/Ring/Cartfile
index e336d18..7848fe1 100644
--- a/Ring/Cartfile
+++ b/Ring/Cartfile
@@ -1,3 +1,3 @@
-github "ReactiveX/RxSwift" == 3.0.1
-github "RxSwiftCommunity/RxDataSources" ~> 1.0
-github "pkluz/PKHUD" ~> 4.0
+github "ReactiveX/RxSwift"
+github "RxSwiftCommunity/RxDataSources" == 1.0.3
+github "pkluz/PKHUD"