* Support for multiple domains within --domain-filter

The parameter accepts a comma separated list of domains with or without trailing dot. Example: --domain-filter="example.org, company.test.,staging.com". Closes #247 and #229

* Add boilerplate header

* Add documentation for methods and structs

* use StringsVar for the domain-filter flag

* go fmt

* Remove camel case from tests

* Revert changes in README.md

* Move DomainFilter to provider package

* Make a new slice and copy elements to it

* Update CHANGELOG.md

* docs: change minor spelling mistake

* adjust docs before the v0.3.0 release

* minor fixes

* docs: add missing dot

* docs: add missing dot

* docs: drop line

* docs: drop another line

* adjust documentation

* update main readme

* checkbox for releases, add --txt-owner-id flag in description

* docs: minor weird character fixes [ci skip]

Bug in question: https://github.com/kubernetes-incubator/external-dns/issues/154

This is fixed in 0.2.1

* feat(aws): support hostnames as endpoint targets

* docs: describe how to run ExternalDNS on AWS

* docs: update changelog with CNAME feature

* docs: update changelog to include AWS documentation

* fix(aws): test that updating records removes the old value

* feat(google): add CNAME support to Google provider

* fix(source): sanitize source and target hostnames

* docs: update changelog to include latest changes

* docs(aws): mention that ExternalDNS takes full ownership of a hosted zone

* fix(aws): switch route53 tests to use endpoint pointers

* docs: add TODO to remove record filtering once ownership is in place

* docs: elaborate the docs, add a faq section

* docs: fix a messed up command

* docs: update docs to reference v0.1 release

* docs(faq): fix stray whitespace

* docs: restructure docs for a leaner README

* docs: move first run section back to main readme

* docs: fix references to packages

* docs: fix reference to gke tutorial

* docs: fix missing source flag in examples

* docs: fix missing provider flag in examples

* docs: mention ingress support in main readme

* docs(tutorials): add tutorial on how to use external-dns with GKE

* docs(gke): document how to setup a zone with its parent