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
Switched to a regular expression based split of links to make sure URIs that contain commas do not interfere with the rather simplified splitting algorithm we used before.
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.
