Fix scope on maven plugin api and remove duplicate

[hazendaz]

currently in the pom this is listed 2 times. Please remove the duplicate 2.0 one and mark the other 'provided' as required per maven.

        <dependency>
            <groupId>org.apache.maven</groupId>
            <artifactId>maven-plugin-api</artifactId>
            <version>2.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.maven</groupId>
            <artifactId>maven-plugin-api</artifactId>
            <version>${maven.version}</version>
        </dependency>

[ssvaidyanathan]

done