Release 0.3.2

Added

• Implemented sorting for str64 columns.
• write_csv can now write columns of type str64.
• Fread can now accept a list of files to read, or a glob pattern.

Fixed

• Fix the source distribution (sdist) by including all the files that are
  required for building from source.
• Install no longer fails with llvmlite 0.23.0 package.