K8s Test Cleanup and Service PTR

middleware/auto: Close to reader

Close the reader, stop leaking file descriptors.

Change the CI setup for K8s to be simpler. Now it just creates a
set of objects via a yaml file, making it very easy to modify
the tests.

Implement PTR for services.

Provide TTL examples for cache middleware. Fixes: #364

Add interaction docs to make non invalidation for cache middleware
clear. Cache might serve stale records. Fixes: #403

Provide TTL examples for cache middleware. Fixes: #364

Add interaction docs to make non invalidation for cache middleware
clear. Cache might serve stale records. Fixes: #403

Fixes several typos in docs.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

This fix adds Codecov badge to README.md so that coverage data shows up.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Fix typos

* Simplify code

* Fix error usage

Only manual operation is editing the source - even that could be
automated but meh.

* When no records match, reply with NXDOMAIN

* Implement in IsNameError

* case for unexposed namespace. k8s integation tests

* Fix imports order. Lower case of err strs.

This reverts commit 15ab38f0.

Add type to default template

* middleware/file: also react to rename events.

* React to all events

Up till now we would only chase 1 CNAME. Spec requires we will chase
all. This PR add support for this.  Up to 8 CNAMEs are chased (this
could be longer, by just checking for cycles, but 8 seems enough for
now).

Also add RRSIG of the first CNAME for DNSSEC.

* middleware/cache: cache 0 will be capped at 5

cache 0 would return TTL=0 records, up that to the documented minimum of
5 seconds.

* middleware/cache: check for 0 TTL

Handle 0 TTL differently and return an error, we might need to
special case this in the future.

Remove unwanted flags (mostly from glog) and keep the ones we need.

Slightly better errors reporting for failing to sent a notify.

Be more explicit in the logs when a notify fails.
New notify error message looks like:

2016/11/07 18:21:42 [ERROR] Notify for zone "example.org." was not accepted by "8.8.8.8:53": rcode was "SERVFAIL"

Correctly pick up secondaries

When multiple secondary are specified make sure they are picked up.

Fixes #393 #398

Extent typify to check the transfers, dynamic updates and notifies.
Extend *cache* to not put these in the cache.

Fixes #393

The watchers were still trying to process raw v1 objects which
failed to be added to the store. This meant new services and
namespaces created after CoreDNS started would not be discoverable.

Add a filter function that converts watch events with v1 objects
to events with api objects.

Small tweak to tag docker image with current release number.

* add extra test

* middleware/auto: fix crash when calling empty handler

Don't call the next middleware, we should be auth. for this zone
getitng into this path we should respond with ServFail.

Fixes #388

Lint and vet the curret code add docs about adding a git post-commit
hook that performs these actions after each commit.

Don't panic on a non-existent directory. Add test for it as well.

Fixes #384

A NSEC record is need to deny any other name that might exist.
Also don't blindly perform the interface conversion when getting
glue for NS records as they now may include RRSIG - also add tests
for that.