Add MarkupSafe library to third_party (dependency for Jinja2 2.7)

As of version 2.7 Jinja2 depends on the MarkupSafe module.
http://jinja.pocoo.org/docs/intro/#markupsafe-dependency

We are already using Jinja2 v2.6 as a template engine for code generation
in Blink, and we'd like to upgrade it to v2.7.1, for various improvements.
MarkupSafe used to be part of Jinja2, but as of v2.7 has been factored into
a separate module, thus we need to add it separately.

For reference, MarkupSafe (and Jinja2) are also included as third-party libraries in Google App Engine.
https://developers.google.com/appengine/docs/python/tools/libraries27

Blocking:
Issue 23506004: Update Jinja2 (Python template library) to 2.7.1 + add OWNERS
https://codereview.chromium.org/23506004/

Source:
https://pypi.python.org/packages/source/M/MarkupSafe/MarkupSafe-0.18.tar.gz
MD5: f8d252fd05371e51dec2fe9a36890687
SHA-512:
0438ddf0fdab465c40d9afba8c14ad346be0868df654c11130d05e329992d456
a9bc278551970cbd09244a29c77213885d0c363c951b0cfd4d9aa95b248ecff5

Review URL: https://chromiumcodereview.appspot.com/23445019

Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: e85b42fb36cff8bb1854ec0f73d9f8255c3ee3ae
12 files changed