Change haystack INDEX_NAME when running tests

This uses the [same technique sayit uses][1] for detecting when
we're running tests, however instead of switching to the SimpleEngine,
we're overriding the INDEX_NAME setting by appending '_test' to it.

Originally I did try using the SimpleEngine, but it [caused errors][2]
when running the tests. Doing it this way also means our tests run
in an environment that's closer to production.

[1]: https://github.com/mysociety/sayit/blob/master/spoke/settings/base.py#L231
[2]: https://gist.github.com/hecticjeff/11ed0b34b101f87cee3d
Fix bug with generating breadcrumbs

There was a subtle bug introduced in 584d1fe6 meaning that the test for
co-ordinates was always being run, even if a url name mapping had been
found, which meant if the url didn't match a co-ordinate it was always
falling back to the default in the else statement.

Part of #801
Only generate breadcrumb links for actual urls

This adds some extra checks to see if the breadcrumb url can be
resolved, if it can, then we generate the breadcrumbs as normal, if we
can't resolve it then we still display the breadcrumb, but we don't make
it a link.

This also solves the problem of some of the breadcrumbs being relative
rather than absolute links, which cause 404 errors.
Fix placeholder text in SA search form

Closes #910
Add failing test for #937 on url reversal for hansard/committee
[Zimbabwe] Update navigation people and other links.
Adapt script to apply changes directly onto the popolo document
Add biographies to the Popolo document
Remove mention of pulling in profiles from south africa data loading instructions
Keep the code near the data it applies to.
Fix #937 by setting current_app for reverse urls

requires https://github.com/mysociety/sayit/pull/91
Limit to 5 speeches per category by default
Merge remote-tracking branch 'origin/issues/940-add-profiles-to-popolo-file'
Merge remote-tracking branch 'origin/breadcrumb-fixes'
Merge remote-tracking branch 'origin/elasticsearch-test-index'
Override templates in SayIt that reference URLs that no longer match.
Merge branch 'issues/937-fix-reverse-urls'
Merge remote-tracking branch 'origin/issues/933-sayit-noreversematch'
Extract person to speaker mapping code for reuse
Add basic code that lets you search for a person's speeches under a section - relies on changes in SayIt in the 'store-sections-in-search-index' branch