Relative path for json file in connectgmail

Use relative path instead of an absolute path that differs per install.
Also use forward slash since it works everywhere.
Turn into maven project

Easier to handle the dependencies
Suppress restriction warning caused by JavaFX

Something to do with not every java vm having JavaFX. For example
openjdk (which gave me issues on linux that led me to install the oracle
java). We will simply enforce usage of Oracle Java at this point in
time.
add dependencies: tuio, twitter4j, facebook4j

Via Maven