Added Journal of Magnetic Resonance Imaging to styles.

Created new style for the Journal of Magnetic Resonance Imaging. Could not find exactly this style anywhere in the current list.
See http://www.ncbi.nlm.nih.gov/nlmcatalog/?term=1522-2586 and point 8 of https://github.com/citation-style-language/styles/wiki/Style-Requirements.

ISSN: 1053-1807
EISSN: 1522-2586