fix: properly handle boolean attributes

Fixes #37
Closes #98
Excluding the transpiler from karma.

This fixes the issue with the transpiler
appearing twice with different coverage
results in the report on coveralls.io.

Cf here: https://coveralls.io/builds/622626
The following files appeared twice
./hsp/transpiler/processString.js
./hsp/transpiler/processAST.js
./hsp/transpiler/formatAST.js