installer: fix node quotacheck for non-/ geardata

Bug 1138889 - quota config broken if /var/lib/openshift is a mount point
https://bugzilla.redhat.com/show_bug.cgi?id=1138889

* Fixed faulty sed regex for adding usrquota to /etc/fstab.
* If the mount point had an incorrect selinux label, quotacheck
  could fail due to selinux denials, so run restorecon first.
* Finally, the restorecon of the quota file failed unless the
  mount point is /, so added a / to make it work.
<openshift.ks> apply firewall changes with configure_host step
Merge pull request #450 from detiber/confFirewall21

<openshift.ks> apply firewall changes with configure_host step
Merge pull request #451 from sosiouxme/bz1138889-quotacheck

installer: fix node quotacheck for non-/ geardata
install: enable xpaas install experience

https://trello.com/c/5e9f2ejA/275-5-xpaas-preparedness

Changes to openshift.sh so that when the fuse cartridge is released, we
have an "xpaas" profile that can work with it out of the box.

This also makes some generalized changes:
* Introduce a setting for proxy ports per gear
* Introduce a setting for district UID range
* The SNI proxy is installed, configured, and firewall ports opened
* Introduce settings for SNI proxy port range

Then, when a node is designated with node_profile=xpaas:
* External ports per gear defaults to 15
* The SNI proxy defaults to listening at 10 ports
* xpaas districts are created with reduced capacity (to match 15 ports)
install: organize header comments

The comments, particularly the parameter listing, had grown somewhat out
of control. They are now organized into hopefully-logical sections with
a table of contents.

No code changes were made.