Fix sass-convert --recursive.

Closes #1435
Watch the working directory for changed partials with sass --watch.

Closes #1393
Closes #1411
Set exit code 65 when the compiler fails due to a Sass error.

Closes #1439
Fix/work around rubocop errors.
Bump VERSION to 3.4.5.
adding appveyor configuration to this branch off stable
use a larger build matrix

new versions of Ruby (with DevKit) have been installed:
  - 1.9.3 x86 (C:\Ruby193 - default in PATH)
  - 2.0.0 x86 (C:\Ruby200)
  - 2.0.0 x64 (C:\Ruby200-x64)