bitbake: layerindexlib: Initial layer index processing module implementation

The layer index module is expected to be used by various parts of the system
in order to access a layerindex-web (such as layers.openembedded.org) and
perform basic processing on the information, such as dependency scanning.

Along with the layerindex implementation are associated tests.  The tests
properly honor BB_SKIP_NETTESTS='yes' to prevent test failures.

Tests Implemented:
   - Branch, LayerItem, LayerBranch, LayerDependency, Recipe, Machine and
      Distro objects
   - LayerIndex setup using the layers.openembedded.org restapi
   - LayerIndex storing and retrieving from a file
   - LayerIndex verify dependency resolution ordering
   - LayerIndex setup using simulated cooker data

(Bitbake rev: fd0ee6c10dbb5592731e56f4c592fe687682a3e6)

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/bin/bitbake-selftest

@@ -22,6 +22,7 @@ sys.path.insert(0, os.path.join(os.path.dirname(os.path.dirname(__file__)), 'lib
 import unittest
 try:
     import bb
+    import layerindexlib
 except RuntimeError as exc:
     sys.exit(str(exc))
 
@@ -31,7 +32,10 @@ tests = ["bb.tests.codeparser",
          "bb.tests.event",
          "bb.tests.fetch",
          "bb.tests.parse",
-         "bb.tests.utils"]
+         "bb.tests.utils",
+         "layerindexlib.tests.layerindexobj",
+         "layerindexlib.tests.restapi",
+         "layerindexlib.tests.cooker"]
 
 for t in tests:
     t = '.'.join(t.split('.')[:3])