Add gurobi package

Signed-off-by: Shea Levy <shea@shealevy.com>
Add gurobi token server service

Not yet tested, I don't have a license yet

Signed-off-by: Shea Levy <shea@shealevy.com>
Add gurobi client module

Not yet tested, no license yet

Signed-off-by: Shea Levy <shea@shealevy.com>
Add gurobi to the system packages if the configuration specifies a license

Signed-off-by: Shea Levy <shea@shealevy.com>
D'oh

Signed-off-by: Shea Levy <shea@shealevy.com>
Fix compatibility with Nix < 1.6

Nix 1.6 (accidentally) changed the semantics of strings like
"${path}/bla", so this happened to work on 1.6 but not before.
Make more tests release-critical
mysql: Remove ancient, unsupported versions
php: Update to 5.4.20
mysql: Update to 5.5.34

CVE-2013-3839
mysql: Move all versions into the same directory
mysql: Update to 5.1.72
postgresql: Update to latest versions
grub: Make assertion lazier
Make manual generation not depend on the user's configuration

Previously changing the value of certain options in configuration.nix
would cause the manual to be regenerated, because some option defaults
depend on the configuration.  This is undesirable because rebuilding
the manual is kind of slow.  So now the manual reflects an empty
configuration.

The downside is that this requires another call to fixMergeModules,
which adds about 14% to evaluation time.  Probably worth it.
Rename newOptionAttrSetToDocList -> optionAttrSetToDocList
mkEnableOption: Add a period at the end of the description
Don't enable acpid for VirtualBox guests

It's no longer needed for ACPI shutdown, since logind handles this
now.
Remove obsolete pre-systemd compat stuff
Fix PAM resource limits