Update the plugin to a Maven 3.0.4 platform.

* Parent pom updated to current version from upstream.
* Maven core components pulled from that version.
* Obsolete Maven artifacts removed: maven-project, maven-toolchain.
* maven-compat added to avoid rewriting code that uses the ArtifactResolver.
* Other dependencies brought to current.
* enforcer configured to disable unwanted check from parent.
* junit up to 4.11 to get access to rules.
Move all plugin configuration to @nnotations.

* fix pom configuration of maven-plugin-plugin to work for annotations.
* edit all the mojos and parameters.

Since the default value of defaultValue is "", I suppressed defaultValue = "".

Since the default value of a boolean is `false`, I suppressed defaultValue = "false".

In a few places I found that the doc, the @parameter defaultValue, and the
initial setting of the property disagreed. I made them agree. All the ITs pass, but
it might disturb someone's project which is accidentally depending on the
incorect setting in the @parameter (treating the doc as the definition of
correct).
Merge branch 'maven-3.0.4'

This branch updates the NAR plugin to the Maven 3.0.4 platform.

Conflicts:
	src/main/java/com/github/maven_nar/Compiler.java
	src/main/java/com/github/maven_nar/NarSystemMojo.java