Merge pull request #19 from dpford/master

Range filtering added (date, numbers, etc.)
make a more_like_this function available in templates
Merge pull request #20 from rosskarchner/more_like_this

make a more_like_this function available in templates
fixed handling of filters to not include pagination as search params
makes a get_document function available in templates
Merge pull request #23 from dpford/pagination_fix

fixed handling of filters to not include pagination as search params
Merge pull request #22 from rosskarchner/get_document_function

makes a get_document function available in templates
fix for related links issue
Only include filters in ES query if they have values