Merge pull request #55 from edx/ormsbee/btalbs_xblock_wb_fix

Update workbench and XBlock versions to grab workbench HTML fix.

requirements/base.txt

 # edX Internal Requirements
-git+https://github.com/edx/XBlock.git@d38ea051#egg=XBlock
-git+https://github.com/ormsbee/xblock-sdk.git@3c092c27#egg=xblock-sdk
+git+https://github.com/edx/XBlock.git@923978c5#egg=XBlock
+git+https://github.com/ormsbee/xblock-sdk.git@295678ff#egg=xblock-sdk
 
 # Third Party Requirements
 django==1.4.8