Added sysinfo (System Information) functionalities

- More informative messages are displayed during startup, to make it
  easier to identify what system and environment Hercules is running.
- Git/SVN revision detection is improved, separating the source version
  (cached at compile time) from the runtime version, in case the user
  updated their working copy without recompiling the server. Git
  version detection is also more reliable, in case a non-default branch
  is used.
- The get_revision script command has been removed (as it was useless
  to begin with, after the switch to git). An alternative will be
  provided later, for feature-probing purposes.
- The patch was tested under Linux (Gentoo / gcc 4.7 on i686 and x86_64,
  Debian 6 / gcc 4.4 on i686, Raspbian / gcc 4.6 on armv6l, CentOS 5 /
  gcc 4.1 on i686, CentOS 6 / gcc 4.4 on x86_64, Linux Mint 15 / gcc 4.7
  on x86_64, OS X Mountain Lion / clang 5.0 and gcc 4.8 on x86_64,
  Cygwin-NT-5.1/gcc 4.8 on i686, FreeBSD 8 / gcc 4.2 on i386, FreeBSD 9
  / gcc 4.2 on amd64, FreeBSD 10 / clang 3.3 on amd64, NetBSD 5 / gcc
  4.1 on i386, NetBSD 6 / gcc 4.5 on amd64, OpenBSD 5 / gcc 4.2 on
  amd64, Solaris 11 / gcc 4.5 on i86pc, Windows 7 / Visual Studio 2012
  on x86, Windows 8 / Visual Studio 2010 on WOW64, Windows 8.1 / Visual
  Studio 2013 on WOW64.

Signed-off-by: Haru <haru@dotalux.com>
Follow-up to 916aa169daeda32c823c0c704b86d1be1fb831b7

- Stat server update to go along with the sysinfo changes

Signed-off-by: Haru <haru@dotalux.com>
Whitespace cleanup

Replaced some tabs in the middle of the line with spaces.
Thanks to KeiKun for pointing out #ifdef<tab>_COMMON_SYSINFO_H_ and
making me realize how many of them were there.

Signed-off-by: Haru <haru@dotalux.com>
Added version screen to the Travis output

- This helps identifying the build system as well as to ensure that the
  produced executables can start without crashing.

Signed-off-by: Haru <haru@dotalux.com>