Log Message:
Update blockdiag to 1.5.0.

1.5.0 (2015-01-01)
------------------
* Refactor cleanup procedures
* Fix bugs

  - Fix get_image_size() closes Image object automatically
  - Fix pasting Image object failed on SVG mode
  - Fix #61 images.urlopen() got PermissionError on Windows
  - Fix #61 images.open() raises exception if ghostscript not found
  - Fix #62 Use "sans-serif" to font-family property on SVG output \ 
("sansserif" is invalid)
  - Fix #63 AttributeError on get_image_size(); Pillow (<= 2.4.x) does not \ 
have Image#close()