Reencrypt snapcraft credentials

[rvolosatovs]

Summary

Follow-up of #2199

Changes

• Reencrypt snapcraft credentials

Notes for Reviewers

Installed the prerelease version of travis, as suggested by travis-ci/travis.rb#711 (comment) (https://rubygems.org/gems/travis/versions/1.8.12.travis.1116.9 to be exact) and reencrypted the file.

travis encrypt-file -r 'TheThingsNetwork/lorawan-stack' snapcraft.login
encrypting snapcraft.login for TheThingsNetwork/lorawan-stack
storing result as snapcraft.login.enc
DANGER ZONE: Override existing snapcraft.login.enc? |no| yes
storing secure env variables for decryption

Please add the following to your build script (before_install stage in your .travis.yml, for instance):

    openssl aes-256-cbc -K $encrypted_fe6eb417a432_key -iv $encrypted_fe6eb417a432_iv -in snapcraft.login.enc -out snapcraft.login -d

Pro Tip: You can add it automatically by running with --add.

Make sure to add snapcraft.login.enc to the git repository.
Make sure not to add snapcraft.login to the git repository.
Commit all changes to your .travis.yml.

Since travis-ci/travis.rb#678 Travis supports encryption of multiple files includes the filepath in the hash (hence, the change of env variable name in original PR (#2181), however, apparently, this PR broke the encryption command. This PR landed in 1.8.11
In #2199 I reencrypted the file using the old CLI version (1.8.8) using old hashing - not surprisingly, decryption did not work.

#2201 did not revert all the changes and apparently reverted to changes introduced in #2181, hence the env variable names do not change in this PR.

In case this does not work, I will reencrypt everything manually, but let's give Travis team another chance...

Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, database and configuration, according to the stability commitments in README.md.
• Testing: The changes are covered with unit tests. The changes are tested manually as well.
• Documentation: Relevant documentation is added or updated.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.

[coveralls]

Coverage increased (+0.005%) to 73.458% when pulling 529fcfe on rvolosatovs:fix/snapcraft-travis into 959f6d7 on TheThingsNetwork:master.