Added sampling API docs
Added examples to sampling function api docs
Fixed utils/__init__ __all__ list
Wrap _sampling.pyx with sampling.py to include api docs
Fix typo
Update utils docs
Remove docstrings from _sampling.pyx
Renamed factor to block_size
More descriptive sampling docs
Add link to block_reduce
Merge pull request #84 from larrybradley/sampling-apidocs

Added sampling API docs