Implement support for using *.jar pattern in VirtualWebappLoader to specify all JAR...

Implement support for using *.jar pattern in VirtualWebappLoader to specify all JAR files in a certain directory.

This is inspired by Bootstrap.createClassLoader(..) and ClassLoaderFactory.createClassLoader(..).
There is a small difference with regards to ClassLoaderFactory.createClassLoader(..) implementation:
1. I removed the file.canRead() checks as I think that they are not necessary here. I am checking existence and type only.
2. Note that isFile()/isDirectory() are documented to return false if the path does not exist, so using a separate exists() call there is not necessary.

Also three other changes:
1. Added trim() to the tokens.
2. Implemented debug logging.
3. Removed "not for production" warning from the JavaDoc.

An update for the documentation (/config/loader.html) should follow later.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@958615 13f79535-47bb-0310-9956-ffa450edef68