Adds many additional attributes defined in RFC5988 and verifies they work properly in the neutral representation of Link while also being rendered properly in the HAL module.
Related tickets: #100, #417, #235
Previous pull requests: #240, #238, #223, #79
TempalteVariable is now a standalone class. Introduced TempalteVariables wrapper to allow easy collecting of TempalteVariable instances and rendering them in the shortest possible way.
Introduced new Links container element to group a list of links and allow parsing an RFC5988 compatible String representation of links into it. The parsing mechanism is currently regarding the rel attribute only.
Added valueOf(…) factory methods to allow Spring MVC to pick the types up out of the box.