node: improve Node.get_device_map function

Updated the code to more accurately return available block devices on
the node using regular expressions with fdisk and /proc/partitions. This
method also handles a variety of block device naming schemes (e.g.
/dev/hda, /dev/sda, /dev/sdj1, /dev/cciss/c0d0, etc).
node: improve get_partition_map function

Updated the code to properly handle the 'boot' flag and hex system id
output from fdisk. Also improved the partition matching regular
expression to handle a variety of device formats (e.g. /dev/hda,
/dev/sda, /dev/sdj1, /dev/cciss/c0d0, etc)
clustersetup: ebs volume mounting improvements

Use master.get_device_map and master.get_partition_map when mounting EBS
volumes in the default StarCluster plugin.