Upgrade to lumen 5.5

[ibpavlov]

Upgrade to Lumen 5.5

• php requires 7+ now
• update composer packages and requirements to the latest available
• support Laravel 5.5 changes - router, LumenPassport
• Remove unneeded code for $user
• update Travis builds for latest php versions

For issue: #40

Maybe you can create a new branch for old 5.4 and a tag it. So changes for 5.5 are on master and development

[hasib32]

@ibpavlov Pull request is merged. Thank you so much for your hard work.