Upgrade Maven compiler plugins

- error_prone_core to 2.1.1
- maven-compiler-plugin to 3.6.2
- plexus-compiler-javac{-error-prone} to 2.8.2

Change-Id: I20d864c869f2d03f623ea054b6d08e7ee0eb262a
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

pom.xml

@@ -264,7 +264,7 @@
 
         <plugin>
           <artifactId>maven-compiler-plugin</artifactId>
-          <version>3.6.1</version>
+          <version>3.6.2</version>
           <configuration>
             <encoding>UTF-8</encoding>
             <source>1.8</source>
@@ -302,19 +302,19 @@
             <dependency>
               <groupId>org.codehaus.plexus</groupId>
               <artifactId>plexus-compiler-javac</artifactId>
-              <version>2.8.1</version>
+              <version>2.8.2</version>
             </dependency>
             <dependency>
               <groupId>org.codehaus.plexus</groupId>
               <artifactId>plexus-compiler-javac-errorprone</artifactId>
-              <version>2.8.1</version>
+              <version>2.8.2</version>
             </dependency>
             <!-- override plexus-compiler-javac-errorprone's dependency on
                  Error Prone with the latest version -->
             <dependency>
               <groupId>com.google.errorprone</groupId>
               <artifactId>error_prone_core</artifactId>
-              <version>2.0.19</version>
+              <version>2.1.1</version>
             </dependency>
           </dependencies>
         </plugin>