Fix spelling error and add some documentation to _render_config_file_template and related function _extend_env.
Fix spelling error and add some documentation to
_render_config_file_template and related function _extend_env.

elkingtonmcb/cloudbiolinux,AICIDNN/cloudbiolinux,kdaily/cloudbiolinux,heuermh/cloudbiolinux,chapmanb/cloudbiolinux,chapmanb/cloudbiolinux,AICIDNN/cloudbiolinux,pjotrp/cloudbiolinux,joemphilips/cloudbiolinux,chapmanb/cloudbiolinux,kdaily/cloudbiolinux,elkingtonmcb/cloudbiolinux,pjotrp/cloudbiolinux,averagehat/cloudbiolinux,kdaily/cloudbiolinux,chapmanb/cloudbiolinux,pjotrp/cloudbiolinux,averagehat/cloudbiolinux,AICIDNN/cloudbiolinux,lpantano/cloudbiolinux,elkingtonmcb/cloudbiolinux,lpantano/cloudbiolinux,pjotrp/cloudbiolinux,elkingtonmcb/cloudbiolinux,rchekaluk/cloudbiolinux,rchekaluk/cloudbiolinux,heuermh/cloudbiolinux,joemphilips/cloudbiolinux,kdaily/cloudbiolinux,lpantano/cloudbiolinux,averagehat/cloudbiolinux,joemphilips/cloudbiolinux,rchekaluk/cloudbiolinux,heuermh/cloudbiolinux,heuermh/cloudbiolinux,AICIDNN/cloudbiolinux,rchekaluk/cloudbiolinux,joemphilips/cloudbiolinux,averagehat/cloudbiolinux