Parent version updated to Jenkins 1.447

- The plugin is not buildable with current parent version 1.410 and JDK 7

[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Internal error in the plugin manager executing goal 'org.jenkins-ci.tools:maven-hpi-plugin:1.67:apt-compile': Unable to load the mojo 'org.jenkins-ci.tools:maven-hpi-plugin:1.67:apt-compile' in the plugin 'org.jenkins-ci.tools:maven-hpi-plugin'. A required class is missing: com/sun/mirror/apt/AnnotationProcessorFactory
com.sun.mirror.apt.AnnotationProcessorFactory
[INFO] ------------------------------------------------------------------------
[INFO] For more information, run Maven with the -e switch
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 18 seconds
[INFO] Finished at: Sat Feb 08 19:15:37 CET 2014
[INFO] Final Memory: 59M/376M
[INFO] ------------------------------------------------------------------------
make: *** [package] Error 1

- Fixed according to

http://jenkins-ci.361315.n4.nabble.com/JIRA-Created-JENKINS-10818-Clearcase-plugin-does-not-compile-on-JDK-7-td3768631.html

"Proprietary API which was used by apt compiler was removed from JDK 7. However the issue itself has been fixed in newer apt compiler, so this problem can be solved by depending on newer Jenkins plugin pom."

- Generated files for development in Eclipse added to .gitignore to prevent an accidental commit.