Add official support for firebird back

Improve error message in case no migration is found (golang-migrate#158)

* Improve error message in case no migration is found

* Return similar error

* Just log the error

* Fix error message

Properly filter out custom query params in MySQL DB driver

Addresses: golang-migrate#272

Let database.Open() use schemeFromURL as well (golang-migrate#271)

* Let database.Open() use schemeFromURL as well

Otherwise it will fail on MySQL DSNs.

Moved schemeFromURL into the database package. Also removed databaseSchemeFromURL
and sourceSchemeFromURL as they were just calling schemeFromURL.

Fixes golang-migrate#265 (comment)

* Moved url functions into internal/url

Also merged the test cases.

* Add some database tests to improve coverage

* Fix suggestions

Update migration docs

Correct and clarify information around empty migrations
Addresses: golang-migrate#244

Merge pull request golang-migrate#227 from zhevron/mssql-params

Fix incorrect syntax errors for MSSQL driver

Update dependencies to resolve: golang-migrate#202

Update packages that depend on the wrong golint import path

Addresses: golang-migrate#202

Use alpine 3.9 for building Docker images

Merge pull request golang-migrate#167 from arpando/fix/DocumentNilError

Fix document nil error