HADOOP-15540 with some initial review tuning
- ordering of imports
- rely on azure-auth-keys.xml to store credentials (change imports, docs,.gitignore)
- log4j -> info
- add a "." to the first sentence of all the javadocs I noticed.
- remove @Public annotations except for some constants (which includes some commitment to maintain them).
- move the AbstractFS declarations out of the src/test/resources XML file into core-default.xml for all to use
- other IDE-suggested tweaks
Review the tests, move to ContractTestUtil assertions, make more consistent to contract test setup, and general work to make the tests work well over slower links, document, etc.