Revert a series of commits about @Shippable, because unfortunately Shippable has basically lost all its advantages over Travis CI after it was upgraded to V2.

This reverts commit 5772f8b7dc4db776cf37308ea1ece4820f94d7f5.

This reverts commit 65439bf54ce0ec24d956b49e25d71693b153412e.

This reverts commit 2933705877c083a0b6a6ee7e9bf83972479e528a.

This reverts commit 1c7b1355df4913daa2679607257540278f08d60f.

This reverts commit 7db3f733e792bf6d2cfaa6b6bbd8f1496ff51f89.

This reverts commit a260fc419019e470cdea26adc449bff232ee59e9.

Closes #67
use the svg badge instead of png