fix error Azure::BlobService

[tsara27]

There's an error like this when I tried to save the file. NameError (uninitialized constant Azure::BlobService):

I have fixed it by modifying it into Azure::Blob::BlobService

[adamdilek]

@unosk can you set azure gem version in gemspec ?

[monteirobrena]

I've the same error. Any news?

I'm using:

 azure (0.7.5)
    azure-core (~> 0.1)
 carrierwave (0.11.2)
    carrierwave-azure (0.0.3)

[monteirobrena]

@unosk some expectation to merge this PR?

[razvanmitre]

Is this repo even mentained anymore? @unosk

[nunommc]

@tsara27 on my fork of your branch I added also gem.add_dependency 'azure', '>= 0.7.5' as the ::Blob you've added wouldn't work with prior versions (I don't know exactly since which version)