Adding 'expo' command for support with latest version of Expo.

[haysclark]

Per expo/exp project commit. 053fd31

exp has been replaced by Expo CLI. Read more…

Ideally, SpinJS could be updated to support the newer expo-ci command: expo.

This could be purposely done as an API breaking change to SpinJS, thus the fix would be version 1.x.x. Or the 'expo' command could live alongside with the older 'exp' command.

[larixer]

@haysclark Hi Hays. Thank you for the issue! I think adding expo command support alongside with exp would be great.

[haysclark]

Sorry about the commit spam, I was cleaning up my commit messages. GitHub used to delete the orphaned commits.

[larixer]

@haysclark No worries, its fine