fix for travis and ruby 1.8.7
Merge pull request #205 from sharpyfox/travis_fix

fix for travis and ruby 1.8.7
Explicitly close and unlink WickedPdfTempfile

Ruby docs states a good practice when using Tempfile is to explicitly
close and unlink temporary files within an ensure block rather than
relying on the garbage collector.
Merge pull request #206 from lightswitch05/master

Explicitly close and unlink WickedPdfTempfile