Ivy Cleanup and Third Party Update

Reworked for cleaner ivy implementation.
* No longer copies ivy jar local to project.  It copies it to cache when
it doesn't exist there.
* Removed older style Ant task for ivy that is no longer necessary
* Using ivy classpath rather than retrieve to stop copying jars local
* _external is now simply source and class files
* Jars no longer under _external or _lib.
* _lib and org.apache.ivy no longer present - manually delete these for
first build after this integration
* Removed logback-access.  This is not used.
* Merged ivy.xml and ivywork.xml.
* Arranged ivy.xml in alphabetical order
Updated third party
* Updated tomcat to 7.0.37
* Updated groovy to 2.1.0
Build cleanup
* Removed mention of _lib
* Removed unnecessary _external jar fileset
Change log cleanup to more closely match pull requests / issues.
Ivy task must be defined