A round of post-deadline cleanup of SLIK code.

Based on / inspired by code review done by John on SLIK code (originally written
by various members of SLIK team).
This round of changes is mostly documentation improvement, code simplification,
copyright updates and small bug fixes.
Optimizing class Object to treat contiguous Buffers as ordinary contiguous byte buffers.
Merge branch 'master' of ssh://fiz.stanford.edu/git/ramcloud
Augmenting the unit test for Object constructor from Buffer
Made 'docs' make target not depend on 'python-docs', so that it does not
need to compile RAMCloud. Now it should run on ramcloud.stanford.edu to
generate the nightly docs.
Moving functions related to index key to IndexKey class.
In RamCloudTest, separating out tests for the two indexing operations.
Client now specifies maxNumHashes for IndexedRead operation.
Nit: Modifying variable name in a protobuf.
Cleaner handling of index RPCs when the index doesn't exist.

If an index doesn't exist, the IndexRpcWrapper cannot send the rpc.
This can be indicated in the status of the RPC.
However, in many cases of Index RPCs, the caller will not care
and can make the operation be a no-op by faking a response.

Main changes include:
1. Added a new Status: STATUS_UNKNOWN_INDEX and corresponding
   Client Exception.
2. IndexRpcWrapper sets the status of an rpc for which the index
   doesn't exist to STATUS_UNKNOWN_INDEX in a virtual function
   indexNotFound.
3. IndexRpcWrapper completes the rpc without sending it
   (sets state to FINISHED).
4. Subclasses of IndexRpcWrapper can override indexNotFound().
   RamCloud::LookupIndexKeysRpc, MasterClient::InsertIndexEntryRpc
   and MasterClient::RemoveIndexEntryRpc override this function
   to set the status to STATUS_OK (because they want to treat this
   as a no-op), and the LookupIndexKeysRpc also fakes a response.
5. Also added unit tests.
Some cleanup for ObjectManager class (and corresponding unit tests).

Alphabetizing functions within various organization units,
better indentation for function signatures, removing an extra
function declaration (that wasn't defined).