Relax rails dependency

[MaximeD]

This relax the rails dependency to allow subversions of rails 6.0 to
use the gem.

In order to simplify the dependencies of the lib, instead of requiring
all rails, just the relevant part are required.

Travis has also been updated to run on rubies 2.5 and 2.6.

[coveralls]

Coverage decreased (-0.02%) to 98.856% when pulling cbfb03a on MaximeD:relax_rails_6_dependency into 45bba17 on sungwoncho:master.

[chevinbrown]

This relax the rails dependency to allow subversions of rails 6.0 to
use the gem.

Travis has also be updated to run on rubies 2.5 and 2.6.

Nice ❤️.
Why the manifest changes?

[MaximeD]

Thanks 😄
The manifest was added because it is required by sprockets 4, which was updated when I did a new bundle after relaxing rails’ dependency.
But not sure that won’t do as latest sprockets requires ruby >= 2.5, so that might break for users still using ruby 2.4. I’ll try to see if I can relax the dependency without having sprockets upgrading itself 🤔

[chevinbrown]

Thanks 😄
The manifest was added because it is required by sprockets 4, which was updated when I did a new bundle after relaxing rails’ dependency.
But not sure that won’t do as latest sprockets requires ruby >= 2.5, so that might break for users still using ruby 2.4. I’ll try to see if I can relax the dependency without having sprockets upgrading itself 🤔

Makes sense! Really, sprockets shouldn't be a dependency...I only passively maintain this gem as an artifact of my last job. 😢
Either way, I can accept this change if you're not able to keep it slim.

[MaximeD]

So in the end, I changed the dependencies to only require the parts of rails that are really needed by this gem. This way no need for sprockets anymore!

Let me know :)

[chevinbrown]

@MaximeD fantastic!

[MaximeD]

Awesome, thank you!