Re-implement the charm-event legacy API endpoint.

Only support what strictly required by "juju publish".
This is based on Jay's work.
Proper error checking in the charm-event endpoint.
Add a missing test for the legacy charm-event endpoint.
Improve docstrings and comments in the charm-event legacy endpoint.
Abstract out a function to retrieve the entity Bazaar digest.
Legacy charm-event endpoint: handle digest not found race condition.
Merge pull request #244 from frankban/add-legacy-charm-event

Re-implement the charm-event legacy API endpoint.

Only support what strictly required by "juju publish".
This is based on Jay's work.
Refactor charmstore to use new helpers in jujutesting.
Update dependencies.
Fixing mistakes in import grouping.
Merge pull request #245 from frankban/use-testing-json-assertions

Use testing json assertions

Big branch (apologies!) but mostly mechanical.

Also updated dependencies.
Added debug status for elasticsearch

Added debug status for elasticsearch

Added debug status for elasticsearch

Check ES Database, refactor test for valid elastic search set up

Refactor test for valid elastic search set up

Refactor test for valid elastic search set up

Use ClusterHealth strcut instead of map to represent the health status of ES

Check the internal status of the Cluster Health

Move formatting of ClusterHealth

Added JSON unmarshall test
Fix Unit test with httptesting
Merge pull request #239 from fabricematrat/elasticsearch-debug-status

Elasticsearch debug status
reformat dependencies.tsv with UTC times
Merge pull request #247 from rogpeppe/098-reformat-deps

reformat dependencies.tsv with UTC times

No actual dependency changes here.
internal/v4: add viewbox to icons that do not have one

Some web browsers require a viewbox, but not all icon.svg
files have one. The standard library's encoding/xml package
does not cope well with name spaces, so we use a temporarily
forked version with fixes.

We could be more efficient when processing icon.svg files
that already have a viewbox, but since icons will be cached
anyway and it's reasonably efficient, we use the simplest approach.