Implement basic queries for enrollments

# Description

Implemented enrollments queries per:
- Region
- State
- City

The *census_year* parameter is *mandatory* and should be included in all requests.

The "/enrollments" route supports the following parameters

- aggregate: metric to aggregate, can be {state, region, city}. When no parameter is supplied or the parameter is not supported, the API assumes the whole country.
- id: record identifer of the metric to aggregate (e.g. one specific state or region), it only applies when the aggregate parameters is passed and is valid. Again, when no parameter is specified, the API assumes the whole range of values the metric can take (e.g. all states or all regions).
- adm_dependency_id: administrative dependency identifier, the possible values are shown in the Table 1.

- location_id: location identifier, its possible values are given in Table 2.

# Tables

*Table 1:* Administrative dependency table.

| adm_dependency_id | name           |
|---------------------------|---------------|
| 0                                          | All records  |
| 1                                          | Federal        |
| 2                                          | Estadual     |
| 3                                          | Municipal   |
| 4                                           | Privada       |

*Table 2:* Location table.

| location_id  | name            |
|----------------|---------------|
| 0                        | All records  |
| 1                        | Urbana        |
| 2                        | Rural            |

# Response Format

The API returns a JSON array with name "result" where every array has following attributes:
- name: Name of the metric (e.g. name of a state, city or region)
- total: Total number of enrollments for the selected metric and given parameters.

# Examples
Retrieve the number of enrollments of 2014 for the whole country:
> /api/v1/enrollments?census_year=2014

Retrieve the number of enrollments of 2013 for a given region:
> /api/v1/enrollments?census_year=2013&aggregate=region&id=1

Retrieve the number of enrollments of 2012 for all rural locations in the state of Paraná:
> /api/v1/enrollments?census_year=2012&aggregate=state&id=41&location_id=2

Retrieve the number of enrollments of 2012 for the North region:
> /api/v1/enrollments?census_year=2012&aggregate=region&id=1

See merge request !5

Signed-off-by: João Victor Tozatti Risso <jvtr12@c3sl.ufpr.br>

Signed-off-by: João Victor Tozatti Risso <jvtr12@c3sl.ufpr.br>

Tests



See merge request !3

Fixed XML output

Closes #6

See merge request !4

Closes #6

Signed-off-by: João Victor Tozatti Risso <jvtr12@c3sl.ufpr.br>

Signed-off-by: João Victor Tozatti Risso <jvtr12@c3sl.ufpr.br>

Conflicts:
	libs/routes/api.js

- Rename /matriculas to /enrollments
- Add initial support for parameters in the enrollments route

Conflicts:
	package.json

Add cors

Added CORS (Cross-Origin Resource Sharing) to API. This way the API allows different URLs to use it.

See merge request !1

Related: #3

Signed-off-by: João Victor Tozatti Risso <jvtr12@c3sl.ufpr.br>

Implement the following aggregations:
- per-state
- per-region
- country

In order to use these queries one should use the /api/v1/matriculas route. When
the 'agregar' query parameter is set, one could use the values 'estado' and 'regiao'
to run the aggregation for state and region, respectively. Otherwise, if no parameters
are supplied, it defaults to the whole country aggregation query.

Not following any specs