Update plugins to current versions.

maven-compiler-plugin .................................... 3.1 -> 3.2
maven-jar-plugin ......................................... 2.4 -> 2.5
maven-javadoc-plugin ................................ 2.9.1 -> 2.10.1
maven-release-plugin ................................... 2.5 -> 2.5.1
maven-site-plugin ........................................ 3.3 -> 3.4
maven-source-plugin .................................... 2.2.1 -> 2.4
maven-surefire-plugin .................................. 2.17 -> 2.18
org.codehaus.mojo:animal-sniffer-maven-plugin .......... 1.11 -> 1.13
Merge pull request #1043 from stefanbirkner/plugin-updates

Update plugins to current versions.