Avocado

- Drop NumPy and SciPy dependencies for built-in k-means algorithm
- This is to simplify the install process and remove heavyweight dependencies for use of a single algorithm
- Move export templates under `avocado/templates` to remove the need to add `avocado.export` to `INSTALLED_APPS`
- Add new `QueryProcessor` class (see [052e7d0](https://github.com/cbmi/avocado/commit/052e7d0b12922d48434229f671f8193f72df9007) for details)
- Change `DataField.search` to _not_ return an iterator
- This enables downstream slice without needing to evaluate the data structure (primarily for `SearchQuerySet` instances)
- Add `avocado.events` package for simple tracking of events such as accessing a `DataConcept` or `DataField`
- Add `DataQuery` model which represents a joint data structure of a `DataContext` and `DataView`
- The JSON corresponding to each structure is stored, rather than referencing instances directly. This is for simplicity.
- Add support for n-grams search and fix outstanding search tempalte (see [a5c273e](https://github.com/cbmi/avocado/commit/a5c273e59e0fde80fb3213ccbedaaa4d3406cf8f))
- Note, re-indexing may take much longer than before since it is now correctly indexing the field values

- Add convenience manager method on `DataView` and `DataContext` for get the default template
- Improve unicode representation for templates

- Add support for Django 1.5
- Increase minimum version of ModelTree 1.1.5
- Add a Haystack `search_sites` module for convenience when integrating in a project
- Remove default search results size of 10
- This is arbitrary and has caused confusion that it was truncating results
- Augment the `language` text directly to `DataContext` JSON attributes
- This reduces the overhead for clients to parse the language dict separately
- Modify context validation to disable invalid nodes
- This takes a more passive approach to validating context nodes, but prevents the context from getting in an unusable state. Validation errors result in the node being disabled.
- Add `template` and `default` fields to DataContext and DataView
- This enables the use case of differentiating template contexts and views vs. user-defined ones. The `default` flag enables marking a template as the default one to be used so there is a starting point for clients.
- The dict representing the JSON data can be passed into the `DataContext` and `DataView` constructors directly for convenience
- Other field values can still be defined using keyword arguments `DataContext({...}, name='My Context')`
- Modify verbose name for 'in' to be 'is either X, Y or Z' and the negated form to 'is neither X, Y, nor Z'
- Change container-based operators to use the `Exact` and `NotExact` text for single value lists

- Backport context node schema from 2.1
- This is a backwards compatible port of the context node changes in Avocado 2.1 specifically to:
- Support the `field` key instead of `id` as the field identifier
- Support the `concept` key which is used to scope the `field`
- Support branches without children or one child to act as containers

- Fix possible mis-ordering of formatter keys and fields

- Add implementation (and fix) for handling the SELECT DISTINCT/ORDER BY behavior in databases more transparently