Added Server checkers

[sansyrox]

Base PR of issue : fossasia/susi_linux#464
Added Server Checker functions that check if the local server is active or not

[hongquan]

I think the behaviour of "having a background task to check and switch between local server and remote server" is just a specific need of an application that uses this lib.

When you are making a lib, you have to make it agnostic to application. If this lib can only be used for one application, better baking it into application.

There are other issues:

• Server URL is hardcoded. If an application is deployed to a machine where port 4000 is already occupied by some other service, they have to make local SUSI server running on different port. But your lib is hard-coded with port 4000, how can they use it?

I refuse to merge this PR.

[sansyrox]

@hongquan , I don't understand. What do you mean by "lib" ?

[hongquan]

"lib" = "library", I mean this "susi_api_wrapper". You moved it out of "susi_linux" to act as a library.

[sansyrox]

Must merge for this PR to work .

[sansyrox]

@hongquan @Orbiter please have a look again.

[hongquan]

I will leave @Orbiter to decide to merge this or not. My opinion is to refuse this, because I don't agree to put a background task into a library. It should be done in application (susi_linux), not library (susi_api_wrapper).