Updated dependencies for core
Updated dependencies for Polaris
Updated dependencies and generated code for PCL
Fix concurrent stream access issues on WinRT

Provides a workaround for the oplock issues under WinRT by providing a
Stream implementation that automatically reopens itself when an oplock
error occurs. This fix also requires disabling the background writer
thread under WinRT and so it also extends the API for
BinaryFilePageStore to allow the use of background page write to be
specified in the constructor.
Fixed package references for portable desktop tests
Fixed GraphTests to use configured paths rather than hardcoded ones
Added ToString implementation
Fixed tests for new constructor
Added test for running multiple update txns consecutively

This is a duplicate of a test that is currently failing under PCL to see
if the same failure occurs under standard .NET.
Reposition the stream after oplock recovery
Ensure eviction rules are always applied
Updated iOS dependencies and fixed unit tests
Merge branch 'feature/issue150' into develop