This patch completely  gets rid of fping
 - replace all fping invocations with TcpPing calls
 - update documentation accordingly.
 - associated cleanups (use constant for localhost IP, use more sensible
   defaults for TcpPing and _use_ those)

Reviewed-by: iustinp

Since modules are not directly executables, remove the shebang from
them. This helps with lintian warnings.

Also make the autogenerated _autoconf.py contain two comment lines at
the beginning, like the other modules.

Reviewed-by: ultrotter

- Move symlink to “ganeti” to top dir
- Add ganeti.config_unittest.py to tests to be run
- Make sure everything is built before tests are run

Reviewed-by: iustinp

dot.

Reviewed-by: iustinp

Reviewed-by: schreiberal

We currently require that hostnames are FQDN not short names
(node1.example.com instead of node1). We can allow short names as long
as:
  - we always resolve the names as returned by socket.gethostname()
  - we rely on having a working resolver

These issues are not as big as may seem, as we only did gethostname() in
a few places in order to check for the master; we already required
working resolver all over the code for the other nodes names (and thus
requiring the same for the current node name is normal).  The patch
moves some resolver calls from within execution path to the checking
path (which can abort without any problems). It is important that after
this patch is applied, no name resolving is called from the execution
path (LU.Exec() or other code that is called from within those methods)
as in this case we get much better code flow.

This patch also changes the functions for doing name lookups and
encapsulates all functionality in a single class.

The final change is that, by requiring working resolver at all times, we
can change the 'return None' into an exception and thus we don't have to
check manually each time; only some special cases will check
(ganeti-daemon and ganeti-watcher which are not covered by the
generalized exception handling in cli.py). The code is cleaner this way.

Reviewed-by: imsnah

Reviewed-by: iustinp, imsnah

To be used to replace the currently fping(8) based reachability test.

Reviewed-by: imsnah