[x86_64] Fix test failures on 64-bit.

This commit does not actually change the Kiwi.xcodeproj settings to
support 64-bit architectures, it merely fixes test failures that
occur when building for that architecture.

- Fix STAssertEquals failures for mismatched types.
- On 32-bit architectures, `@encode(BOOL)` is equal to "c"; on
  64-bit architectures it is equal to "B". As a result,
  `KWObjCTypeIsNumeric` is no longer true for `BOOL` types. This commit
  adds a `KWObjCTypeIsBool` utility method and allows BOOL values to be
  queried for their `-numberValue` as on 32-bit by modifying
  `KWValue.m`. This fixes failures in the
  `KWBeTrueMatcherTests`, which use `+[KWValue valueWithBOOL:]`.
- Add tests for KWObjCUtilities.
Merge branch 'master' into x86_64

Conflicts:
	Kiwi.xcodeproj/project.pbxproj
Fix build errors when compiling `let` under ARC

Created a KW_LET_REF macro to abstract the complexity of getting
pointer to a __block variable on the heap. It works like so:

    (__autoreleasing id *)      /* (5) cast result as `id *` */
    (
      (void *(^)(void))         /* (3) cast back to a block */
      KW_ARC_AUTORELEASE(       /* (2) if not ARC, autorelease the block */
        [^{
          void *ref = &var; return ref;
        } copy]                 /* (1) block returns a pointer to a copied block object */
      )
    )()                         /* (4) invoke the block immediately */

This resolves two issues that occurred under ARC:

- Using `__autoreleasing id *` to capture a reference to a `__block id`
  variable gave this error:

      initializing '__autoreleasing id *' with an expression of type
      '__strong id *' changes retain/release properties of pointer

  Changing to `__strong id *` yielded this:

      passing address of non-local object to __autoreleasing parameter for
      write-back

  Using `void *` opts us out of reference counting, resolving the errors.

- Switching to `copy` instead of `Block_copy` caused the static analyser
  to reveal an issue where the block is never released when compiled
  without ARC. Added the KW_ARC_AUTORELEASE macro that wraps the block
  in a call to `autorelease` when ARC is not present.
Merge pull request #370 from modocache/x86_64

[x86_64] Fix test failures on 64-bit.
Merge pull request #413 from sharplet/let-ARC-fix

Fix build errors when compiling `let` under ARC
put travis task in Makefile, replaced w/ xcodebuild temporarily
Added the KWLet header to the appropriate copy build phases.
Merge pull request #419 from jessedc/bug/kwlet-buildphase

Added the KWLet header to the appropriate copy build phases.
Merge eeafa34 into test spy feature branch to get 'let' fixes.