user has an array of tokens
for now, user gets a single token at a time
added revoked and isRevoked to token model; simplfied compare token (it no longer checks isExpired, end users should do this); added unit tests for revokation
cleaned up language
added validation unit test for default state
added clear db test helper
renamed unit tetss
consistent spacing
moved coverage instrumentation code into test helper
added integration test folder
added issue and revoke token methods to user
added integration tests for issue/revoke token methods on user, since they are database-dependent
updated tests to use assert.instanceOf where relevant; improved descriptions
added mongodb service to travis
updated issue token to pass the raw token string to the callback, which is the only time the raw token string is exposed; added compareToken method and associated integration tests
Merge branch 'feature-user-tokens' into develop