Sparse-dot-topn-for-blocks

- fix python 2 install problem, but failed

- Make long description use markdown format

- update readme file name

- fix the problem when pip install by tar.gz;
- update meta-information of package

- improve the function import layer. Now awesome_cossim_topn can be used directly after `from sparse_dot_topn import awesome_cossim_topn`.
- improve the module installation

- Release the first version