Add contribution guidance

Add CONTRIBUTING.md that points to the same document in chef-cookbooks
Add mention of the contribution document in the top of the README.md
Merge pull request #331 from claco/contributing

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ha clustering set from rabbitmq settings
Merge pull request #332 from rackerjoe/master

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DE264: Change nova.scheduler.filters.standard_filters to nova.scheduler.filters.all_filters
Merge pull request #333 from odyssey4me/DE264

DE264: Change deprecated scheduler standard_filters to all_filters
Cleanup to fix deprecation warnings
Move ram_weight_multiplier setting into scheduler options partial
Merge pull request #334 from mattt416/deprecate_least_cost_functions

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Document nova["scheduler"]["ram_weight_multiplier"] attribute
Merge pull request #335 from mattt416/update_readme

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Move attribute for scheduler filters

Move the attribute for nova_scheduler_default_filters from nova/platform
to nova/scheduler. This is not a platform-specific option.

New attribute is nova/scheduler/default_filters
Merge pull request #336 from DavidWittman/move-scheduler-filters-rebase

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Explicitly install python-memcache(d) when installing metadata / consoleauth services
Merge pull request #337 from mattt416/install_memcache_client

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Allow override for vncserver_listen

Migrations fail when vncserver_listen != 0.0.0.0 because the libvirt
XML config for that VM contains the vncserver_listen address. When an
instance is migrated to a new host, VNC tries to bind to that interface,
which fails miserably.

This commit allows the operator to override the vncserver_listen config
by setting nova/libvirt/vncserver_listen. If this value is not defined,
it will default to the current lookup method using search.

Fixes rcbops/chef-cookbooks#399
Merge pull request #338 from DavidWittman/399-vncserver-listen

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Fixed quoting on cachemodes option
Merge pull request #339 from jrcloud/de281-novaconf-syntax-error

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DE286: Sort memcached server list in nova.conf

Sort array elements by 'host' key (array of hashes).  Fixes #567