Added common module for blob, queue and file.

[sima-zhu]

Currently, blob, queue and file share the exactly same common pkg. I would be better to add a common module for the reasons:

1. We do not have duplicate code for 3 services.
2. No need to make extra efforts every time we update the common module. Like SAS token.

Work need to be done for common module.

1. Extract the common func to a new module.
2. Added Junit tests
3. Remove the common pkg in each service and the refer to the common module.

[sima-zhu]

@JonathanGiles @jianghaolu @alzimmermsft