tracking.js: convert new altitudes to user units for flot
Merge pull request #216 from Turbo87/tests

Replaced nosetests by pytest
Travis: Generate assets before running tests
requirements: Added Flask-Testing package
setup.py: Removed Flask-DebugToolbar package from dependencies
tests/model: Extracted AppTest class
tests/model: Merged test classes
tests: Moved AppTest class into parent package
tests: Added create_app() method to AppTest class
tests/tracking: Merged code into AppTest class
tests/lib: Use AppTest class where possible
tests: Renamed bootstrap_db to BOOTSTRAP_DB
tests/frontend: Use AppTest class for TestController
tests/lib: Use AppTest class in test_sql.py
tests: Moved functions into AppTest class
tests: Removed outdated comments in test_authentication