Improve loadconfig docs
Remove test duplication
Use actual range in the `EnumTest.Range`
Improve test coverage for `Enum.reverse_slice/3`
Add `@spec` for `Enum.reverse_slice/3`
require otp 17.3 to pass on travis
Merge pull request #2949 from jw2013/travis

Update .travis.yml
warning about dumb terminal just irritates users
Merge pull request #2950 from tonini/remove-dumb-terminal-warning

warning about dumb terminal just irritates users
Improve `Enum.reverse_slice/3` performance
More than thrice for lists
Around 35% for other collections
Only shut down Logger if the application is being actually started
Merge pull request #2948 from lexmag/improve-reverse_slice

Improve `Enum.reverse_slice/3` performance and more
improved performance of Integer.undigits/2
Merge pull request #2951 from Kabie/Integer.undigit

Improved performance of Integer.undigits/2
this resolves #2952 compile error
Merge pull request #2953 from liveforeverx/fix_compile_error

resolves #2952