Added single line comment support in less/sass for javascript parser

[mokkabonna]

Will try to add python as well

ref #326

End of line comments are not supported yet, it is moved to the next line.

[bitwiseman]

😄 Might include a few more tests, if you can think of them. Other than that and python implementation parity, looks good.

[mokkabonna]

I think that should be it. If accepted I will move on to other less issues, like

.rule {
  &:hover {
  }
}

turns into

.rule {
  &: hover {
  }
}

Have already an implementation of that for javascript.

[andrewjmead]

Please release a new npm version 😄 I would love to use this!