Overhauled (and moved) libsite; streamlined installation

Now that there is a libsh, it makes sense to move libsite there.

Took this opportunity to clean up the long list of messy global
environment variables therein, and thus did the same for each use-case
of these variables.

Also fixed up the makefile to ensure first-time user experience is
seamless - thanks to travis-ci this was easy to do!

Added `SITE_CORE_BIN'.

Clean-up installation/uninstallation/purge (makefiles).
Cleaned `module/unit': cosmetic, wording

The two sections previously called DYNAMIC and STATIC were irrelevant,
and have hence been renamed to what they actually are: `prime', and
`execute'.

Excess noise removed (too many hash-lines).

General cosmetic clean-up.
Updated `dynamic.csv' for net: closes nima/site#3

Fixed `:net:portping' arguments.
Updated `module/util': doc, update

Doc:

    Fixed the usage docstring for `util:secret()'

Update:

    `g_GPG_KEY_PATH' is no more, and site will look for a GPG key
    based on the active profile instead.  No more guess work.
Updated `module/net': new, fix

New:

    `:net:portpersist' - keep trying for an open port using socat, and
    do so `${attempts}' times.

Fix:

    The internal and private functions should not have variable
    arguments, this is the work of the public function; fixed
    `:net:portping()'.

    Fixed small bug with `:net:portping()' where tldid was not set in
    the case where the fqdn was external.
Added `module/net' unit tests: closes nima/site#7
Updated `module/dns': updated `:dns:fqdn()'

This function now tries to determine if the hint supplied is already
a fqdn (by means of known fqdns and `:dns:qialified()'), and if not,
then do it will fall back to the existing logic/code.

This should simplify things for most callers that had to do this work
themselves, and speed things up in the case that the hint supplied was
already an fqdn.
New `module/softlayer'

New site module that interfaces with `extern/softlayer'.
Updated `libexec/softlayer': flag for cache added

Added a programatic flag (variable) to enable/disable caching, and
set that to false as softlayer API calls are not too costly.
New `module/mongo': mongodb site module
Amended `bin/ssh': persist on down hosts

If a host is not responding on port 22, then keep trying it until it
does - and only then make an ssh connection attempt.

This is now used in `::remote:tmux()' instead of the ssh binary
itself.
Updated `module/gpg': minor update
Added `module/util' unit tests: for nima/site#4
Updated `README.md': travis and links