new dicing strategy working for United States

cleaned up try/except/continue ohi-science/ohicore#40
Merge branch 'master' of https://github.com/bbest/ohiprep
split out LE model output layers for digestion by toolbox ohi-science/ohicore#29
updated layers for OHI toolbox ingestion ohi-science/ohicore#29
Merge branch 'master' of https://github.com/bbest/ohiprep
adding image to describe accessing RStudio via web browser to neptune for Wiki:Setup
Merge pull request #33 from bbest/master

buffers, LE and neptune.nceas.ucsb.edu/rstudio