Resolve BOOL vs. char type bug

Updates the type checking in OCMBoxedReturnValueProvider's
handleInvocation method so it's closer to the system used
by the main OCMock project on TOT.  The new implementation
uses a helper method, -[NSValue getBytes:objCType:], which
treates 'B' and 'c' types as equivalent.

Note: NSValue+OCMAdditions and the meat of the new implementation
of handleInvocation are both copied from the main OCMock project
(at revision erikdoe/ocmock@999b843).  Anyone looking for a useful
history of this code will need to search in the main OCMock project.
Small changes for compatibility with Xcode 5 Preview.
Fix OCMock boxed value unit tests

We no longer necessarily raise an exception when boxed value types
don't match.  If the types can be converted losslessly then we do
not raise an exception.  This commit changes the old testRaises*
test to attempt a stub and return with actually incompatible types
and adds a new test, testDoesNotRaise*, that does a stub and return
with different but compatible types, verifying that no exception is
raised.
Fix the check for whether we should use `_objc_msgForward_stret`.

I'm not sure if erikdoe/ocmock was mistaken to originally use `__LP64__`
as a proxy for `_objc_msgForward_stret`'s availability or the SDK changed,
but as of the 7.1 SDK `_objc_msgForward_stret` is available unless compiling
for ARM64.
Describe BOOL type arguments correctly in argumentDescriptionAtIndex

Adds a case for argType 'B' in NSInvocation+OCMAdditions'
argumentDescriptionAtIndex method.  The additional case and the
utility method it uses (boolDescriptionAtIndex:) are from
erikdoe/ocmock@77400c22.
Merge pull request #20 from inkling/golden/fix_bool_64_bit

Resolve BOOL vs. char type bug