Release from Travis CI for build number 320

Merge pull request #89 from waghanza/crystal_0.33

Update to crystal 0.33

Release from Travis CI for build number 317

Merge pull request #86 from waghanza/crystal_0.31

Upgrade for crystal to v0.31.0

Release from Travis CI for build number 311

[skip ci] bumped version 0.2.10

[skip ci] bumped version 0.2.10

v0.2.9

Release from Travis CI for build number 307