Fix for Issue 64

[rlodge]

A proposed fix for issue #64 . Also adds the ability to configure the location of the docker configuration file if it's in a non-standard location.

[bkmeneguello]

This must be merged!

[dflemstr]

This looks reasonable but I would like the input from somebody else e.g. @davidxia wrt. the correct use of the docker-client.

[mattnworb]

LGTM overall. Thanks for the PR!

[mattnworb]

Might be nice to log something here in case the user is expecting a Server to be found

[rlodge]

Sure.

[mattnworb]

@rlodge would you be willing to add something to the README and/or changelog describing how to use this?

[rlodge]

Yes, I can give you another pull request against master with that. Something like:

In CHANGELOG.md

1.3.4 (unreleased)

• Add support for using maven settings.xml file to provide docker authorization (Fix for Issue 64 #65)

and in README.md

Authenticating with maven settings.xml

Since version 1.3.4, you can authenticate using your maven settings.xml instead
of docker configuration. Just add configuration similar to:

<configuration>
  <repository>docker-repo.example.com:8080/organization/image</repository>
  <tag>latest</tag>
  <useMavenSettingsForAuth>true</useMavenSettingsForAuth>
</configuration>

You can also use -Ddockerfile.useMavenSettingsForAuth=true on the command line.

Then, in your maven settings file, add configuration for the server:

<servers>
  <server>
    <id>docker-repo.example.com:8080</id>
    <username>me</username>
    <password>mypassword</password>
  </server>
</servers>

exactly as you would for any other server configuration.

Let me know if that sounds like what you're looking for.

[mattnworb]

Looks perfect to me!

[rlodge]

Ok. Added pull request #72 with the documentation.