updating download section in README.md for v 1.0.3

Merge pull request pwittchen#27 from pwittchen/update_readme_for_v1.0.2

updating library version in README.md file

Merge pull request pwittchen#20 from pwittchen/issue_17_update_readme

updating app version and min sdk in README.md file

Merge pull request pwittchen#12 from pwittchen/issue_10_download_section

adding download section to README.md file