Proton 0.9 alpha 1

Hi Everyone,

I've put together an alpha for proton 0.9. There are a couple of motivating
factors for introducing an alpha stage into the release process this time:

- there are some new APIs as well as changes to existing APIs that are
worthy of some extra review
- the install has changed a bit to accommodate the package structure that
comes along with the new APIs
- this is the first release from git

Given all these things I figure we might need a slightly longer release
cycle than usual, so I put together an alpha and posted it in the usual
places.

Source tarballs can be found here:
- https://people.apache.org/~rhs/qpid-proton-0.9-alpha-1/

Java binaries here:
- https://repository.apache.org/content/repositories/orgapacheqpid-1022

This being the first release from git, I've somewhat arbitrarily chosen a
process and encoded it into the bin/release.sh file. Any
comments/suggestions/improvements on the process are welcome.

--Rafael