Added support for empty index files
Prevent min/max from windef.h interference

This resolves compilation problem for sidx_api.cc

http://stackoverflow.com/questions/13416418/define-nominmax-using-stdmin-max
Merge pull request #33 from mlt/nominmax

Prevent min/max from windef.h interference
Merge pull request #32 from cloudant/empty_index

Added support for empty index files