Fix typos
Fix typos
Clarify Python/Django requirements

Nothing really prevents Django 1.3 from working but the tests won't run with
it -- it doesn't have `override_settings()`.

Some code already prevents Graphite-web from running on Python 2.5. Travis
doesn't even support it so it's hopeless to claim 2.5 support.

This patch syncs requirements with what we actually test on Travis, which is
the sanest approach.
Remove uses of sys.exc_info in favor of the py2.6+ syntax
Stop referencing INSTALL
Update render_api.rst
2.6 or greater
Add missing import on /dashboard
Merge pull request #799 from brutasse/fix/missing-import

Add missing import on /dashboard
Merge branch 'master' into fix/versions
Merge pull request #794 from brutasse/fix/versions

Clarify Python/Django requirements
Merge pull request #694 from ifdattic/patch-1

Fix typos
Add missing trailing slash in nginx config example