New Sensor Structure

[oscgonfer]

A different way of handling the sensor implementations was started to make things easier and try to homogenize the whole structure. Ideally benefits of this new approach (in branch https://github.com/fablabbcn/smartcitizen-kit-21/tree/channels) are:

1. Sensor objects are created in runtime, not consuming RAM memory in principle
2. Indifferent if the sensor is on the Urban Board I2C bus or on the Aux Port I2C bus
3. Cleaner and more homogeneous implementation

As a first step, this new implementation would keep the same sensor ids as usual, and test the new data model, https://github.com/fablabbcn/smartcitizen-api/issues/241 with the current implementation or this new structure.

Further down the line, the idea is to send sensor ids with a "hash" composed of different variables to be documented, such as the current sensor id, and the bus in which the sensor is located. This would allow a mux to have duplicated sensors and each of them be uniquely identifiable.