Include self links in normalization

[stephenprater]

Objects embedded in collections can include links elements including their self link. This link is not included in the normalized data structure, regardless of the if you pass endpoint etc.

I can't think of any reason to exclude these links - so I modified the normalize method to always include self links in the normalized data if they are present.

[coveralls]

Coverage increased (+0.06%) to 98.23% when pulling cc8a223 on stephenprater:include-embedded-links-in-normalization into 81d7172 on yury-dymov:master.

[yury-dymov]

Good catch, ty!