Build:Tests: Fix custom build tests, verify on Travis; name Travis jobs

Build:Tests: Fix custom build tests, verify on Travis; name Travis jobs

This commit fixes unit tests for the following builds:

1. The no-deprecated build: `custom:-deprecated`
2. The current slim build: `custom:-ajax,-effects`
3. The 4.0 (#4553) slim build: `custom:-ajax,-callbacks,-deferred,-effects`

It also adds separate Travis jobs for the no-deprecated & slim builds.

Apart from that, add intuitive names to Travis jobs. Otherwise it's hard to see
at a glance that a particular job is running on Firefox ESR, for example.

Ref gh-4577
Ref gh-4596
Closes gh-4600