Update environmental-microbiology.csl

Added sort by date order to inline citations.
Changed et al formatting in bibliography so that 
et-al-min and et-al-use-first are set to the 
values required by Environmental Microbiology
outlined at http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291462-2920/homepage/ForAuthors.html
change position of sort tag

The sort tag must come before the layout tag.  Now validates successfully with http://simonster.github.io/csl-validator.js/
Merge pull request #703 from ctSkennerton/master

Update environmental-microbiology.csl