#155 -  Fix issue related to timeout only setting the azure timeout but not the Net::HTTP client

Fix issue #155.

#### Fix Details
When specifying the timeout for method create_block_blob as follow:
```ruby
blob_options = {
    :content_type => "application/octet-stream",
    :timeout => 15*60 # 15 minutes
}
```
A "Keep-Alive: timeout=900" is added to the HTTP header. This is later extracted inside the http_request.rb to determine whether or not the Net::HTTP client should use its default timeout or replace it with the specified value(in our example, 900)