Merge pull request #73 from anha0825/master

Corner case type spec fixes
updated metadata docs
changed Object Metadata -> Custom Metadata
Merge pull request #74 from basho/dip_metadata_docs

Added a section on updating metadata
Allow for javascript functions in spec

The spec has been adapted to be in line with the online
documentation found at
http://docs.basho.com/riak/latest/references/appendices/MapReduce-Implementation/

It now allows for both anonymous javascript functions,
as well as named built in functions, and anonymous functions
that are stored in riak.
Correct spec for inputs

The input specs in the documentation online
(http://docs.basho.com/riak/latest/references/appendices/MapReduce-Implementation/)
and also in the tests, show that you can pass
inputs as a list of {{bucket, key}, AuxParams}.
The specs mistakenly had these written as
{bucket, key, auxparams}.

This has now been updated to allow dialyzer to
pass on correct usage.
Merge pull request #76 from Aircloak/master

Updates to spec's in riakc.hrl
Added @headerfile tag.

So that doc for data types defined in the
headerfile is also generated.
Merge pull request #77 from srijan/master

Add @headerfile tag in src/riakc_pb_socket.erl
get(...) can return unchanged, not {error, unchanged}.