Ensure urls use ascii encoding

As of Ruby 2.0.0, the default encoding is UTF-8. This will cause the
GoogleSafeBrowsing::Canonicalize unit tests provided by Google to fail
due to an "invalid byte sequence in UTF-8". Forcing the URLs to be
encoded in ASCII-8BIT (binary) first resolves the issue.
Merge pull request #5 from bethcrb/canonicalize_urls

Ensure URLs use ASCII encoding
Merge pull request #4 from bethcrb/master

Update gem to be compatible with Ruby 2.0
Add rspec as default rake task
Merge branch 'chores/default_rake_task'
Bump to version 0.5.1

* Ruby 2.0 compatible
* Default rake task for rspec
Add .travis.yml with ruby versions
Don't append mac to chunk builder specs
Merge pull request #6 from mobiledefense/chores/travis_ci

Integrate with Travis CI
Define contribution in README
fixup! Define contribution in README
fixup! Define contribution in README
Merge pull request #7 from mobiledefense/chores/contribution_documentation

Define contribution in README
Show Travis CI status in README
Merge branch 'chores/travis_icon'
Don't duplicate 'DISTINCT' SQL keyword

`uniq`, when in the AR query context, adds the
`DISTINCT` SQL keyword to your queries. Explicitly
setting the `select` with a distinct and calling
`uniq` is redundant. Further, pluck is better when
only querying for a single column as it prevents
the full loading of AR model instances.

However, the `pluck` method was not available in
this context. I was getting this error in the Chunk
Helper specs:

    Failure/Error: GoogleSafeBrowsing::ChunkHelper.build_chunk_list.
    NoMethodError:
      undefined method `pluck' for #<Class:0x007fb178a50380>
    # ./lib/google_safe_browsing/chunk_helper.rb:22:in `block in build_chunk_list'
    # ./lib/google_safe_browsing/chunk_helper.rb:11:in `each'
    # ./lib/google_safe_browsing/chunk_helper.rb:11:in `build_chunk_list'
    # ./spec/chunk_helper_spec.rb:15:in `block (4 levels) in <top (required)>'
FullHashes can delete themeseves when "subbed"

When a sub chunk is added for an already fetched
FullHash, that full hash should no longer be
matched, as it's removed from the database. Thus
we should delete them from our local cache of full
hashes.
Delete subbed FullHashes when receiving db updates
Remove dummy dev log file
Note that update must be run several times