add pyfs service
code clean
add pyfs service
code clean
fix test case for pyfs
Merge branch 'danielli/pyfs' of https://github.com/edx/edx-platform into danielli/pyfs
Merge pull request #4889 from edx/danielli/pyfs

Adds pyfilesystem service from XBlocks to edx-platform
Revert "Update opaque-keys library to use block_id for html_id for new keys."
Merge pull request #4964 from edx/revert-4960-split/html_id

Revert "Update opaque-keys library to use block_id for html_id for new k...
Use opaque_keys w/ model vars not parsing of url
to generate url.
LMS-11209
JS regex's need to escape special chars
LMS-11260
Update opaque-keys library to use block_id for html_id for new keys.
Catch more places where get_children was giving us version aware references.
LMS-11237