move ciphercontext/aeadciphercontext to bottom of symmetric encryption

Add a bit of additional text to try to make the convoluted AEAD
explanation better.
GCM does not require padding (removing from docs example)
Merge pull request #419 from reaperhulk/gcm-no-pad-required

GCM does not require padding
Merge pull request #418 from reaperhulk/move-contexts

Move ciphercontext/aeadciphercontext to bottom of symmetric encryption
These eggs are sometimes files. We still don't care.
add padding info to docs
Merge pull request #423 from alex/ignore

These eggs are sometimes files. We still don't care.
Merge pull request #424 from reaperhulk/padding-info-for-all

Add padding info to docs
Fixed #428 -- added a changelog
Typo fix
Reformat
Merge pull request #429 from alex/changelog

Fixed #428 -- added a changelog
Prepare to release.
I guess I should take some of the blame.
Ignore six eggs, not a full dozen
Merge pull request #432 from dreid/blame-dreid

I guess I should take some of the blame.
Merge pull request #431 from dreid/release-0.1

Prepare to release.
Document that we're on PyPI
update version to 0.2.dev1 in master
Merge pull request #433 from alex/pip-install-me-captain

Document that we're on PyPI