Fixes setup.cfg, adding current exclude rules, simplified tox.ini to use
setup.cfg and fixed all.

batch is slower than usual insert for a single doc, so, if a document
exceeds the buffer, commit the batch (if any) and put the huge load by
traditional insert.
refactor coming.

Batching is now decided by server, this commits enables it.

Will put a file object on doc json string if read_content is False,
otherwise it will fetch and fill as usual. This is useful for improving
server througput on sync download stream by receiving a bulk-get without
attachments and consume the file-objects as they come.

couchdb lib returns a file object representing the attachment. This
commit dumps the read() call into the wsgi write() call. Doc
representation uses 2 lines also, separating metadata from content.

We were using 1 transaction per doc, which is bad.
Reference:
http://stackoverflow.com/questions/1711631/improve-insert-per-second-performance-of-sqlite
Code now uses 1 transaction for the whole sync.

Instead of getting the attachments as the generator runs, get_docs will
now get as needed. Also, deepcopy solves a memory issue where we were
feeding the couchdb lib view with blobs while modifying it
unintentionally.

create_cmd lacked an explanation and check_schema_versions lacked
reasoning on why it defaults to False.