Avocado

- Fix 67, change `ObjectSet` `created` and `modified` to not be auto-updated
- Increase length of `DataField` `app_name`, `model_name`, and `field_name`
- For extra _long_ field names...
- Change `avocado init` to not prepend the model name to the field name
- Fix and ensure unicode throughout
- Fix the admin action for creating a single `DataConcept` from multiple fields when only one field is selected

- Fix performance in `Formatter` class due to redundant logging
- Add support for `Decimal` types in `Formatter.to_number` method

- Update ModelTree to version 1.1.3 (critical bug fix)
- Add receiver for change Avocado settings during test execution
- Add missing `DataField.coded_values` which the `Formatter.to_coded` relied on

- Add backup utilities for performing metadata data migrations
- New command `avocado migration` for creating a metadata fixture and a corresponding South migration to load the fixture
- Fix bug in R and SAS exporters
- Improve `ObjectSet` class to enable deleting set objects rather than just flagging as being deleted
- Pass the flag `delete=True` when calling a remove-based command, e.g. `foo.replace(objs, delete=True)`

- Fix bug that only checked for NumPy for the for SciPy feature

- Change `HTMLFormatter` to require the `template` argument which may be a template name
or a `Template` object.
- Allow arbitrary `*args` and `**kwargs` to be passed into `*Exporter.write` and
`*Exporter.read` to enable propagation from `write` to `read`
- Add `short_name` and `long_name` for use downstream by clients
- Add [export-specific format as the first _preferred format_](https://github.com/cbmi/avocado/commit/e9865e6631bc62fc63d6cea439dd6d61f4d930d5)
- This is a better default which enables specific formatting when needed. The more general format can be reused across formatters, but when very specific formatting is necessary, this default is preferred.
- Refactor `DataField.model` and `DataField.field` to take in account `Lexicon` and `ObjectSet` models
- The _real_ field and model instances are now named `real_field` and `real_model`, respectively.
- Fix 55, `Lexicon.label` is now correctly used by the `DataView`
- Rename `sync` subcommand to `init`
- Rename `SYNC_ENUMERABLE_MAXIMUM` to `ENUMERABLE_MAXIMUM`
- Remove `orphaned` command in favor of new `check` that performs multiple setup
checks as well as check for invalid datafields.
- Remove `searchable` model field since this applies only to text-based fields.
- This has been repurposed as a deprecated computed property
- Fix 45, allow dict-based settings to be updated, but not overridden
- Remove `DataField.data_source` field
- There was no functional utility of this field and is (currently) out of the scope for Avocado