change R context initialization to store ContextInfo in configuration instead of symbol

...fle.r.engine/src/com/oracle/truffle/r/engine/REngine.java

...acle/truffle/r/engine/interop/ffi/nfi/TruffleNFI_DLL.java

...le/truffle/r/engine/interop/ffi/nfi/TruffleNFI_Utils.java

...ngine/src/com/oracle/truffle/r/engine/shell/RCommand.java

...gine/src/com/oracle/truffle/r/engine/shell/REmbedded.java

...src/com/oracle/truffle/r/runtime/context/ContextInfo.java

...time/src/com/oracle/truffle/r/runtime/context/Engine.java

...me/src/com/oracle/truffle/r/runtime/context/RContext.java

....test/src/com/oracle/truffle/r/test/tck/FastRTckTest.java