Remove maven-license-plugin

This never seemed to work and we will enforce license text via
Checkstyle instead.
diff --git a/pom.xml b/pom.xml
index 015494c..75fe341 100644
--- a/pom.xml
+++ b/pom.xml
@@ -36,73 +36,4 @@
     <module>compute</module>
     <module>enterprise</module>
   </modules>
-  <build>
-    <plugins>
-      <plugin>
-        <groupId>com.mycila.maven-license-plugin</groupId>
-        <artifactId>maven-license-plugin</artifactId>
-        <version>1.9.0</version>
-        <configuration>
-          <strictCheck>true</strictCheck>
-          <encoding>${sourceEncoding}</encoding>
-          <aggregate>true</aggregate>
-          <header>project/src/etc/header.txt</header>
-          <mapping>
-                <xml>XML_STYLE</xml>
-                <java>SLASHSTAR_STYLE</java>
-                <clj>SEMICOLON_STYLE</clj>
-          </mapping>
-          <excludes>
-            <!-- expectation files for unit tests -->
-            <exclude>**/src/test/resources/**</exclude>
-
-            <!-- prevent duplicating license -->
-            <exclude>**/LICENSE.txt</exclude>
-            <exclude>**/header.txt</exclude>
-
-            <!-- high-level project metadata -->
-            <exclude>**/NOTICE.txt</exclude>
-            <exclude>**/DISCLAIMER</exclude>
-            <exclude>**/BUILD.txt</exclude>
-            <exclude>**/CHANGES.txt</exclude>
-            <exclude>**/README.md</exclude>
-            <exclude>**/README.txt</exclude>
-
-            <!-- one-line service registry files -->
-            <exclude>**/*ProviderMetadata</exclude>
-            <exclude>**/*ApiMetadata</exclude>
-
-            <!-- temporary files or those generated by IDE or SCM -->
-            <exclude>**/target/**</exclude>
-            <exclude>**/test-output/**</exclude>
-            <exclude>**/bin/**</exclude>
-            <exclude>**/.settings/**</exclude>
-            <exclude>**/.classpath</exclude>
-            <exclude>**/.dir-locals.el</exclude>
-            <exclude>**/.project</exclude>
-            <exclude>**/.idea/**</exclude>
-            <exclude>**/*.iml</exclude>
-            <exclude>**/*.eml</exclude>
-            <exclude>**/*.ipr</exclude>
-            <exclude>**/*.iws</exclude>
-            <exclude>**/*.DS_STORE</exclude>
-            <exclude>**/TAGS</exclude>
-            <exclude>**/.metadata/**</exclude>
-            <exclude>**/atlassian-ide-plugin.xml</exclude>
-            <exclude>**/.DS_Store</exclude>
-            <exclude>.mailmap</exclude>
-            <exclude>.git/**</exclude>
-            <exclude>**/.gitignore</exclude>
-            <exclude>**/.gitattributes</exclude>
-
-            <!-- Temporary files generated on CloudBees slaves -->
-            <exclude>.repository/**</exclude>
-            <exclude>gc.log</exclude>
-            <!-- binary -->
-          </excludes>
-          <useDefaultExcludes>false</useDefaultExcludes>
-        </configuration>
-      </plugin>
-    </plugins>
-  </build>
 </project>