href urls can be validated
a collection can't be built with invalid top-level hrefs
rm link as symbol because I don't know how to handle with this yet in a reliable way…
validations errors can be identificated
validate top-level links
style fixes + updated readme
style fix
values can be validated
simplified some valid/invalid methods
refactor validator tests to be more specific
rm Symbol as a valid value.

Even though symbols will be permitted, that will be at a program level, not as a value input. Value validator should match the requirements of the CJ spec
validate attributes values
style fixes
links' attributes other than href are validated
validate template values
style fixes
some more style fixes
Merge pull request #18 from carlesjove/validations

Added validations. closes #12