update readme

Merge pull request #281 from godenji/0.2.9

0.2.9 release

Merge pull request #277 from godenji/0.2.8

0.2.8 release

Merge pull request #275 from godenji/0.2.7

0.2.7 release

Merge pull request #259 from godenji/0.2.6

0.2.6 release

Merge pull request #256 from godenji/0.2.5

0.2.5 release

Merge pull request #253 from godenji/0.2.4

0.2.4 release

Merge pull request #247 from godenji/0.2.3

0.2.3 Release

Merge pull request #246 from godenji/0.2.2

0.2.2 release

Merge pull request #244 from godenji/0.2.1

0.2.1 release