New signed off manpages from 8/3/2013
Merge pull request #1395 from Xenapi-Admin-Project/master

Add man pages for some network CLI commands

Man-pages for the following xe commands:
* pif-forget
* pif-list
* pif-param-add
* pif-param-set
* pif-plug
* pif-unplug
* vif-create
* vif-list