Feature and Test Update

This release adds a feature that protects against sysctl values which, when set in /etc/sysctl.conf, may cause operational harm to a system.

The ability has been added to only update the live value and make the disk persistence optional.

Additionally:

• Now use prefetching to get the sysctl values
• Updated self.instances to obtain information about all sysctl values
  which provides a more accurate representation of the system when using
  puppet resource
• Fail if the user attempts to set a value that is not valid on the
  system unless silent is set.
• Updated all tests