redirector is now transition-config

This is the smallest change that will allow this to keep working.
Bigger change to come later.
Update comments to reflect new name for redirector

Also to reflect that we don't import mappings from redirector any more (and
haven't for a long time).
Rename some methods containing redirector

These were either no longer accurate or misleading - the hits import dealt with
hits from pre-transition logs and from post-transition logs - or no longer fit
the new name for the repo. Plus these names are shorter, which is nice.

Conflicts:

	lib/transition/import/site_yaml_file.rb
Rename data/redirector to data/transition-config

If you already have this checked out, you can do one of two things:
* run `bundle exec rake notmodules:sync` to fetch it cleanly
* run `mv data/redirector data/transition-config`
Widen the column width of the mapping type radio buttons
Merge pull request #464 from alphagov/widen_mapping_edit_type_column

Widen the column width of the mapping type radio buttons
Merge pull request #460 from alphagov/rename_redirector

Rename redirector
Use path fields instead of `path_hash`.

We are now using the `path` and `canonical_path` fields throughout the
app, instead of the hashed variants, which we needed because of MySQL
limitations.

We've flipped the index in the `host_paths` table to use the `path`
field, and declared the hash variants as nullable throughout. We're not
removing the columns yet, so that we don't break existing processes that
try to write to them; we'll do that in a subsequent migration.

We also need to index the `canonical_path` field, to replace the index
on `c14n_path_hash`.

This mostly reverts commit 52f0b9fc800a62468ee25d57fe95dec765d1fdc1.

Conflicts:

	db/schema.rb
	lib/transition/import/hits_mappings_relations.rb
	spec/lib/transition/import/hits_mappings_relations_spec.rb
Check if there are conflicts on master when running the build

- This is taken from
  https://github.com/alphagov/specialist-publisher/commit/9a097249c142c6e7146706dfd5fc0282c92f4886, as a thing discussed in tech lead standup that could be useful and passed to me to do via Jamie.
Merge pull request #465 from alphagov/stop-using-path-hash

Use path fields instead of `path_hash`
Merge pull request #466 from alphagov/jenkins_test_merge_result_of_branches

Check if there are conflicts on master when running the build