Reduce verbosity of standard license-maven-plugin execution

[d-ryan-ashcraft]

When working with large, multi-module builds that have both header and license file support from thelicense-maven-plugin, we are finding that a large proportion of our Maven build output is repetitive info from the plugin. In many modules, this approaches or exceeds half of the output. For instance, we generally see this - (but twice, once for header updates, once for license files):

[INFO] --- license:2.2.0.1-SNAPSHOT:update-file-header (update-file-header) @ bar-java ---
[INFO] Adding a license repository jar:file:/Users/foo/.m2/repository/org/technologybrewery/mojohaus/license-maven-plugin/2.2.0.1-SNAPSHOT/license-maven-plugin-2.2.0.1-SNAPSHOT.jar!/META-INF/licenses
[INFO] adding extra resolver classpath://com/presidentbusiness
[INFO] Using classpath extraresolver: com/presidentbusiness
[INFO] Adding a license repository jar:file:/Users/foo/.m2/repository/com/presidentbusiness/president-business-licenses/1.0.0/president-business-licenses-1.0.0.jar!/com/presidentbusiness
[INFO] register GNU Free Documentation License (FDL) version 1.3
[INFO] register GNU General Lesser Public License (LGPL) version 3.0
[INFO] register GNU Affero General Public License (AGPL) version 3.0
[INFO] register GNU General Public License (GPL) version 3.0
[INFO] register GNU General Public License (GPL) version 2.0
[INFO] register GNU General Public License (GPL) version 1.0
[INFO] register Apache License version 2.0
[INFO] register Eclipse Public License - v 2.0 with Secondary License
[INFO] register Eclipse Public License - v 2.0
[INFO] register Eclipse Public License - v 1.0
[INFO] register Eclipse Public + Distribution License - v 1.0
[INFO] register COMMON DEVELOPMENT AND DISTRIBUTION LICENSE (CDDL) Version 1.0
[INFO] register GNU General Lesser Public License (LGPL) version 2.1
[INFO] register MIT-License
[INFO] register BSD 2-Clause License
[INFO] register BSD 3-Clause License
[INFO] register European Union Public License v1.1
[INFO] register President Business Limited Use License
[INFO] register President Business Closed Source License
[INFO] register President Business Client Use License
[INFO] Will search files to update from root /Users/foo/dev/bar-java/src
[INFO] Scan 40 files header done in 160.825ms.
[INFO] All files are up-to-date.

We'd like to turn down some of the standard output, in the following manner:

• Action: Update register {} to be debug level; Rationale: these can be useful in initial project configuration, but not as much once you are applying specific licenses. Only three of these in our case are not default options as well, so it's a lot of output without a lot of impact. This makes it harder to see and understand what is important in the license-maven-plugin output itself as well as for the project as whole.
• Action: Update Using classpath extraresolver: {} to be debug level; Rationale: the prior line effectively covers this already - seems duplicative to have both.

I realize this is a small, nit-picky request. Please feel free to deny it if you see fit. That said, I'll also provide a PR with the changes.