Add mount provider for AIX

Puppet does not provides a correct provider for the mount type on AIX.

A new provider must be created.

Mountpoints in AIX are managed by the commands: crfs, lsfs, rmfs, chfs (http://publib.boulder.ibm.com/infocenter/aix/v6r1/index.jsp?topic=/com.ibm.aix.cmds/doc/aixcmds1/crfs.htm). For nfs mountpoints the commands mknfsmnt, chnfsmnt, rmnfsmnt and chnfsmnt are provided, but they can partially be managed with former commands.

The commands update the file /etc/filesystems that has following syntax:

/usr:
dev = /dev/hd2
vfs = jfs2
log = /dev/hd8
mount = automatic
check = false
type = bootfs
vol = /usr
free = false

/var:
dev = /dev/hd9var
vfs = jfs2
log = /dev/hd8
mount = automatic
check = false
type = bootfs
vol = /var
free = false

*IMPORTANT*: crfs (create) and rmfs (remove), if it is a local filesystem, will create and format (using jfs/jfs2) the needed Logical Volume, or directly remove the Logical Volume losing data.

Two approaches:
1. Use command line tools and operate as expected by AIX commands: Operate on the LV. In that case type should be extended with new parameters (Volume Group, LV name, size...)
2. Modify directly /etc/filesystems files, and manage the Logical Volumes using a LVM type (as in other OS)

risk: medium (manual validate)
probability: medium (aix)
severity: medium (can't manage aix mounts)
test layer (no acceptance setup for aix)