OpenZFS 3993, 4700

OpenZFS 3993, 4700

3993 zpool(1M) and zfs(1M) should support -p for "list" and "get"
4700 "zpool get" doesn't support -H or -o options

Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Ported by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://www.illumos.org/issues/3993
OpenZFS-issue: https://www.illumos.org/issues/4700
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/c58b352

Porting notes:
I removed ZoL's zpool_get_prop_literal() in favor of
zpool_get_prop(..., boolean_t literal) since that's what OpenZFS
uses.  The functionality is the same.