Add toggleable tab min-width

[supremebeing7]

This provides a toggleable solution to #229.

[supremebeing7]

I added specs for this as well, although the new specs as well as about 10 other specs (including all of the others in settings-tabs-spec.js) were failing for me locally, and I didn't have time to do a deep dive to find out what's going on.

I assume, at least for those tests in settings-tabs-spec.js, that the failure is in the setup, so fixing one will fix them all.

[silvestreh]

Unfortunately, like I mentioned in another (unrelated) issue, I won't be able to check this out for a while as my computer is dead and I can't buy a new one. I'll sure try to check it out as soon as possible.

[supremebeing7]

No problem. Thanks for the heads up!

[silvestreh]

I'm not a fan of removing the max-width property from tabs. I can see the benefit of removing the min-width as it would remove the necessity for scrolling the tab bar. If you can update your PR I'll merge it. Thanks!

[supremebeing7]

Even though the max-width is toggleable and _not_ removed by default?

I can definitely update the PR, though I'll just have to keep using my forked copy unfortunately because I have been really enjoying having no max-width.

[silvestreh]

👍 thanks!

[silvestreh]

@supremebeing7, I forgot to mention… run this command git update-index --assume-unchanged styles/custom.less to avoid changing the custom.less file in the future.