Confluence distribution should have activation and mail jar files inside common/lib

Currently confluence distribution has activation and mail jar files inside WEB-INF/lib and we ask people to move them into tomcat's common/lib if they want to use JNDI mail server configuration.

We should distribute those files in the right directory rather then ask people to move them manually.

From http://confluence.atlassian.com/display/DOC/Configuring+a+Server+for+Outgoing+Mail

Confluence distribution: Please move (not copy) the two jar files from the <Confluence-Install>/confluence/WEB-INF/lib directory to <confluence-install>/lib (for Confluence version 2.10 onwards) or <Confluence-Install>/common/lib (for earlier product versions) and restart Confluence.