* Build: use golangci-lint as a make command
* Since gometalinter was deprecated in favor of golangci-lint so it was
replaced by it. Responsibilities held by the gometalinter was moved to
golangci-lint
* There was some changes in implementation (that was also mentioned in
the code comment) between the tools, which uncovered couple errors
in the code. Those issues were either solved or disabled by
the inline comments
* Introduce the golangci-lint config, to make their
configuration more manageable
* Build: replace backend-lint.sh script with make
I renamed `tlsAuth` to `tlsClientAuth` to better describe the fact that
this variable is used to enable TLS client authentication (as opposed to
server authentication) in c04d95f35.
However, changing the name breaks backwards compatibility for existing
installations using this feature and Grafana does not have a
standardised way of migrating changes in the schema:
https://github.com/grafana/grafana/pull/9377#issuecomment-333063543
For reasons of expediency given the severity of the bug (not verifying
TLS), keep the old name.
In c04d95f35 I changed the default for datasource HTTP requests so that
TLS is always verified.
This commit adds a checkbox to allow an admin to explicitly skip TLS
verification, for testing purposes.
* refactor util encryption library so it doesn't have to import log
* add util.SplitString to handle space and/or comma-separated config lines
* go fmt
