initial version of complete reference architecture template
bug fixes to cache commands
fix us-west-1 precise64 ami

Change made in other tempates, doing for this template too. At some
point there was a copy/paste error and the eu-west-1 was used for
us-west-1. See 2cba84135e7a14341f62ff84df638b7445f78ee7
parameterize availability zones; reformat templ maps

Added defaults to some of the settings to make it more likely that
someone will get a stack up and running on the first try: deployment
key and environment tag.

Parameterized the availability zones instead of hardcoding them to
us-east-1. Each region has it's own notion of what is primary and
what is secondary, etc. because it seems that not all capabilities
work in all AZ's.  Specifically I got this error when trying to
create a VPC in us-west-1.

> Value (us-west-1b) for parameter availabilityZone is invalid. Subnets
> can currently only be created in the following availability zones:
> us-west-1c, us-west-1a.

For us-east-1 "B" and "C" are still the primary and secondary so EdX
shouldn't be affected. But in us-west-1 primary=A and secondary=C.
We'll have to learn over time what works best for other regions.

Reformatted the mapping sections to make them easier to read.  Hope
you don't mind.  Much terser and easier to eyeball.

Terser overall description.  Removed the "you'll be billed!" warning.
fix copy/paste dup in memcached stanza
Merge pull request #16 from edx/feature/sef/reference-architecture

parameterize availability zones; reformat templ maps
don't require 2 caches for dev/test cases

Eventually we might want to set these thresholds to have better ranges,
but for trying the stack out I say that we shouldn't require an more
than the minimum number of machines.
Merge pull request #18 from edx/feature/sef/refarch-constraint

don't require 2 caches for dev/test cases
reduce scaling group minimums to 1 for dev/test
Merge pull request #19 from edx/feature/sef/refarch-constraint

reduce scaling group minimums to 1 for dev/test
Merge pull request #20 from edx/feature/e0d/reference-architecture

Feature/e0d/reference architecture