Do HTML escaping on URL routes in the perf dashboard

Summary:
I thought this would be a quick fix, but it turns out to be harder because
HighCharts has a bug where it sometimes incorrectly displays escaped HTML
characters. The workaround was to add a space to the end of every URL route.

Test Plan:
I took the test plan from D12977 :
Run gae_dashboard/generate_perf_chart_json.py to generate some data (I
temporarily changed the default value for preceding_days to 2 in get_series_data
to make this go faster).
Run python -mSimpleHTTPServer 4321 from within gae_dashboard. Click into
webroot and look at the graphs. They show correct url_routes now (although they
still are obnoxiously hard to select due to SVGness).

Reviewers: jlfwong

Reviewed By: jlfwong

Subscribers: benkomalo

Differential Revision: http://phabricator.khanacademy.org/D14104
Escape HTML characters in daily BQ emails

Summary:
Now that URL routes can look like "api.main:/api/internal/foo/<bar>", we need to
be careful that we HTML-escape the strings so they look right in the emails.

Test Plan:
Fingers crossed. My understanding is that this code is hard to test, and a
failure isn't that big of a deal anyway.

Reviewers: csilvers

Reviewed By: csilvers

Subscribers: benkomalo

Differential Revision: http://phabricator.khanacademy.org/D14113