add acs template

add plos one namespace and revise yaml
Right now the acs(American Chemistry Society) template is more like a tex document than markdown document. 
There are three issues:

1. the email in the yaml can't be  a link. I tried to add the hyperref package in the template but the document can't be complied
2. the author can't be more than one, I think this issue due to the conflict between the yaml grammar and some wired definitions in the achemso package
3. achemso package defined many environments while markdown were not support that, so I just write plain tex in the template