ASACORE-1107: AllJoyn Windows builds should treat warnings as errors

We would like to change the AllJoyn build settings to treat warnings as
errors for Windows when compiling at warning level 2. AllJoyn currently
builds at this level so no work would be required, and this will ensure
that any future warnings either get fixed or have an exemption added.

We're proposing this for two reasons: compiler warnings give us a very
inexpensive way to find potential bugs, and this would better match
Microsofts internal development process and prevent new code from
breaking us (we internally build at these settings). Ideally we would
build AllJoyn at a higher warning level, but that will require future
work to cleanup warnings.

CryptoRSA.cc was hitting warning C4309 when building 64 bit due to a
(size_t) typecast assignment to a DWORD. I removed the typecast which
prevents the warning.

Change-Id: Ic4dddb665e2562b9366c9aeb23c825eee4acffa5
Signed-off-by: Rob Smith <robs@microsoft.com>
Merge "ASACORE-1107: AllJoyn Windows builds should treat warnings as errors"