Add freebsd support

[adiclepcea]

This is just a proposition to add support for FreeBSD.
This extends the #49 PR.
This solves #50

[cristianoliveira]

I am not sure about just leaving gnome cause it isn't actually an "OS" hehe we will be lying on the description. Can we try to guess if the system uses gnome at its network manager? I think we can go for something like this.

We will have the linux and freebsd options and we try to guess its network manager. What do you think?

[adiclepcea]

You are right. It would be awkward to use gnome for some operating systems and osx or windows for others (GUI vs OS).
I think we should try and see if it is possible to guess the window manager like you suggested.
One option (although maybe not the best) would be to just look for gsettings. If the program finds gsettings, then it just considers gnome. This would of course not be ok on the systems that have several window managers.
On the other hand, for windows and osx it is somewhat redundant to append the OS to the setup command:
ergo setup osx (since you can already be sure that you run it on osx).
So, perhaps running ergo setup (without a parameter) would be ok, and then, if the system sees that it is running on linux or freebsd, it can check for gsettings.
So the flow would be::
ergo setup results in the systems checking the OS. If it is windows or osx, then it just goes ahead and it runs the setup for osx or windows. If the OS is linux or freebsd, ergo can try to find the command gsettings (or better guess the present window manager) and run the setup for it.
This also opens for more features latter (like KDE or XFCE window manager support) :)

[cristianoliveira]

One option (although maybe not the best) would be to just look for gsettings. If the program finds gsettings, then it just considers gnome. This would of course not be ok on the systems that have several window managers.

I think it could be an option. Also would be simpler to add other managers.

On the other hand, for windows and osx it is somewhat redundant to append the OS to the setup command:

Yeah! The command setup wouldn't need the arg system anymore, cause since we will try to guess the manager for linux/freebsd. We will need just get the current system on runtime.GOOS. Need to test if it can be changed by passing the GOOS env var though and if by changing it could cause some bug for ergo setup

I think we can try this approach :)

[adiclepcea]

You could for example have both Gnome and KDE installed. If, when using ergo, we are using KDE, we could try to start ergo for gnome (with gsettings) just because gsettings is found. I believe that using the env var DESKTOP_SESSION would be a better option (but then we have to take in consideration that there are also Mate distributions or Cinnamon an both of them are gnome). I believe we can try something like:

• if the system is linux or bsd, check for the flag that defines window manager (for osx and windows there is no need to do it)
• if no flag is passed, then try to find it out, else just start the setup for the passed window manager
• if the window manager can be guessed, start the setup for it, else inform the user that ergo cannot guess the window manager and tell it what window managers we know off.

This should clear the problems, but would raise new issues if we decide to go for a service. What happens when you install the service and the window manager is not recognised?