Patch: default value in extension

The default value may, or may not require boxing.  Discovered when
updating to updating to google protocol buffer 2.5 unit tests.
Fix cast warnings in PBArray

The formatted strings for description and PBArrayValueRangeAssert may
be run on 32 or 64 bit platforms.  In both cases, we are only
interested in extracting a string representation of the numeric value.
newline after macros in header
Upgrade to XCTest Framework

All unit tests have been updated to XCTest Framework and test macros
adjusted.
Added shared scheme for CI builds with Travis

The build scheme needs to be marked as shared for Travis CI to build
the library.
Merge branch 'xctest-for-unittests'
Buildable name reference update

Xcode wants to correct a setting in the shared build scheme to remove
references to OCTest.