add execution id to the name to handle multiple plugin executions

When multiple executions of the same plugin were being performed in the same project it was only displaying the duration for the last execution. This adds the execution id to the name to make it unique.

An example of this is using surefire to run both unit and integration tests in different phases. Only the integration run would be recorded.

Also, I'm not sure if the 68 character limit was an arbitrary number, but the likelihood of names being cutoff is greater now. 

```
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.001 s
[INFO] Finished at: 2014-06-12T16:02:08-06:00
[INFO] Final Memory: 11M/62M
[INFO] ------------------------------------------------------------------------
[INFO] Build Time Summary:
[INFO]
[INFO] maven-buildtime-extension
[INFO]   maven-clean-plugin:clean (default-clean) ................. [0.043s]
[INFO]   maven-enforcer-plugin:enforce (enforce-maven) ............ [0.102s]
[INFO]   maven-resources-plugin:resources (default-resources) ..... [0.073s]
[INFO]   maven-compiler-plugin:compile (default-compile) .......... [0.280s]
[INFO]   plexus-component-metadata:generate-metadata (default) .... [0.149s]
[INFO]   maven-resources-plugin:testResources (default-testResource [0.003s]
[INFO]   maven-compiler-plugin:testCompile (default-testCompile) .. [0.067s]
[INFO]   plexus-component-metadata:generate-test-metadata (default) [0.009s]
[INFO]   maven-surefire-plugin:test (default-test) ................ [0.690s]
[INFO]   maven-jar-plugin:jar (default-jar) ....................... [0.216s]
[INFO] ------------------------------------------------------------------------
```