minor glitches in installer

Did some testing with the enhanced install for Tomcat 6.x
and it behaved well. The following are low priority
suggestions for improvement.

If you execute the wsit-on-tomcat.xml installer without
having the environment variable CATALINA_HOME set, you get
a message about a

Missing or inaccessible $

{env.CATALINA_HOME}

/conf/catalina.properties file

While the user could figure out the problem, it would be better
if the error message said that the environment variable CATALINA_HOME
is not set.

The help message when you are on a system with JDK6
mentions the 'install-api' target to use if you just want
to install the webservices-api.jar into the jre/lib/endorsed dir.
That is good, but the syntax shown is

ant install-api

There should be an 'uninstall-api' target.

and it should be

ant install-api -f wsit-on-tomcat.xml
or
ant install-api -f wsit-on-glassfish.xml
#### Environment
Operating System: All
Platform: All
#### Affected Versions
[current]

Source: [https://github.com/javaee/metro-wsit/issues/668](https://github.com/javaee/metro-wsit/issues/668)
Author: glassfishrobot

Inspect wsit-on-tomcat.xml and wsit-on-glassfish.xml, starting with the CATALINA_HOME validation and the JDK6 help text for install-api. Verify the installer reports that CATALINA_HOME is unset, documents the file-specific Ant invocation, and provides an uninstall-api target.

Written by the indexing model from the issue text.