[FIX] requirements: bump up pillow,jinja2 reqs

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We normally stick as close as possible to the version we depend
on in the official DEB packages. This in turn depends on the version of
Debian stable at the time of release - for 9.0 that would be Debian 8
(jessie) and thus Pillow 2.6.1.

However Pillow versions before 3.3.2 and Jinja2 before 2.8.1 suffer
from a few issues that could lead to crashes of Odoo workers.
The bugfixes have been backported in the DEB packages for Pillow,
so users of Debian/Ubuntu LTS versions won't be affected if they are
keeping their systems updated.

However it's worth an exception to our rule for pip users.

requirements.txt

@@ -1,8 +1,8 @@
 Babel==1.3
-Jinja2==2.7.3
+Jinja2==2.8.1
 Mako==1.0.1
 MarkupSafe==0.23
-Pillow==3.1.1
+Pillow==3.3.2
 Python-Chart==1.39
 PyYAML==3.11
 Werkzeug==0.9.6