Make HgUtils async

[victor-torres]

spawnSync blocks NodeJS and we can't have another process/thread running it such as a web worker... We have to refactor HgUtils class to use spawn or exec, the asynchronous version of this command. Basically we need to encapsulate some methods into promises and consume them with .then() in HgRepositoryAsync class.

[victor-torres]

@mrstebo I further investigated based on your suggestions and I can confirm the blame is in the spawnSync guy.

[mrstebo]

I noticed it when I was doing a console.log when checking what hgCommand. Maybe we should have a separate HgUtilsAsync class that can just return promises?

[victor-torres]

Yup. Sounds good. Exactly what I would do.

[victor-torres]

@mrstebo are you up to this one? May I assign it to you?

[mrstebo]

I guess I could have a crack at it 😅

[mrstebo]

Yeah. They seemed to have removed the async stuff in Atom now...
There is an issue here.
And a discussion here