Added Hubble Deep Field image.
Added example and pep8 changes.
Corrected spellings.
Grammar corrections.
Grammar corrections.
Changed travis.yml to install pillow.
pip command correction.
Tab to spaces.
hubble_deep_filed doc string changes.
Changed example to make code compact.
Changed example and hubble_deep_field doc string
autopep8 changes.
Corrected comment in example.
Added method reference to example.
Merge pull request #986 from vighneshbirodkar/blob_example

Blob detection example