don't throw out zeros when processing values spreadsheet
externalize valid spreadsheet cell types /w constant
patch to ignore false values that aren't zero
A function to remove .git extension on install command
remove redundant sentence
add `get_context_from_xlsx` function to allow local xlsx access
Merge pull request #125 from eads/0.9-beta5

add `get_context_from_xlsx` function to allow local xlsx access
add SPREADSHEET_CACHE_TTL and CONTEXT_SOURCE_FILE configuration blocks to default tarbell_config.py template
add space for consistency
handle no s3 buckets case
add config reference
clean up configuration section of docs
Merge pull request #126 from eads/0.9-beta5

docs and bugfixes
tweak intro text
refactor tutorial to use google spreadsheets values
add data section and css section to tutorial
add javascript how to
add images to tutorial
Merge pull request #131 from hbillings/0.9-beta5

tweak intro text & flesh out tutorial
fix temp dir bug