Restict versions and release as 1.4

[oxinabox]

@mmiller-max what do you think?
This initial release will support 1.4, 1.5, 1.6 and will be called TestEnv v1.4

This implements part of #4

Then we can fork off this later to release 1.0.x that supports julia 1.0,
etc

[mmiller-max]

Yeah this is a good idea. Putting the three versions together is good. Do you want to remove the code from other versions ad refactor as you've done in other branches? Could be done in later PRs (or there may be an argument to keep it)

[oxinabox]

Could be done in later PRs

Yeah, I figure no sense changing this now, better to get something working out, can change it later.

Do you approve this one?

[mmiller-max]

How would you see this being used by something like TestReports, which also currently supports a few Julia versions? Would something like having no compat entry for TestEnv result in it having the latest patch version of the compatible branch? Otherwise I'm worried we would need different compat entires for different Julia versions

[oxinabox]

Would something like having no compat entry for TestEnv result in it having the latest patch version of the compatible branch

Yes, if the compat is set to 1 or equivalently 1.0 or 1.0 or 1.0.0 or ^1, or ^1.0 or ^1.0 or ^1.0.0,
then the package manager is free to choose any compatible versiox v with 1.0.0 <= v < 2.0.0
SO it would just chose the latest patch for some compatible version of julia