Slightly Refactor Skills - CV api

Currently in the CV api, under CvVersion.java, a person's skills are initialised as type List<Skills>.

However, Skills itself is an object made up of a list of skills. It's my understanding that everything can actually be contained within one Skills object, rather than a list of them (a list of lists).

This issue would involve:

• changing the allSkills variable in CvVersion to be of type Skills rather than List<Skills>

• making sure nothing breaks in the process

• rewriting the few CV api tests that refer to the allSkills variable