v0.3.3

This contains minor usability fixes.

• 0314e53 - add vcfanno version to header (#140)
• c4c0ae9 - update travis
• 49ef500 - non-zero exit when no args are given
• 6e5a12a - fix help which still mentioned js.
• 9f857a9 - handle missing value in postannotation. closes #116
• 1d140d4 - Misleading Flatten error message (#119)
• 8ffa89c - fix example table format of markdown (#115)