Contrast-Finder v0.4.7

Upgrade-o-meter: just replace the .war file and restart Tomcat

Features:

• #51 - Added a cookie to keep the user's choice on the algorithm to use

Security:

• #44 - Upgrade outdated dependencies: SpringFramework, maven-surefire, maven-war, maven-dependency

Bugs:

• #45 - Fixed docker/pre-requisites: syntax error
• #46 - Fixed maven warnings: 'version' contains an expression but should be a constant

Configuration:

• #50 - contrast-finder.conf: added option to override the default algorithm
• #47 - Added prerequisites for maven (version 3.1)
• #49 - Dockerfile: added HEALTHCHECK instruction

Documentation:

• #42 - Fixed Javadoc warnings
• #12 - Added documentation for releasing a new version