Script doesn't work by default

[gnzlbg]

When using the script it should work by default. Right now I get:

error: Package bitwise v0.1.0 (file:///home/travis/build/gnzlbg/bitwise) does not have these features: unstable

If I comment out the following line:

 - TRAVIS_CARGO_NIGHTLY_FEATURE=nightly

and

error: Package bitwise v0.1.0 (file:///home/travis/build/gnzlbg/bitwise) does not have these features: nightly

if I leave it on.

One solution is to set that line to the empty string

- TRAVIS_CARGO_NIGHTLY_FEATURE=""

but that should be made more obvious. IMO it would be better if the default would be for repos without nightly features to compile as is on nightly, and if some repos need unstable or nightly features the script should explain how to do that, and provide the lines commented out so that just un-commenting them works:

 #- TRAVIS_CARGO_NIGHTLY_FEATURE=nightly
 #- TRAVIS_CARGO_NIGHTLY_FEATURE=unstable

[Ryman]

Could probably use cargo metadata for this:

cargo metadata | jq ".packages[0].features"