Add information about smartphone calibration

[Picaut]

Add a page 'Calibration', with information about how to calibrate a smartphone (texts and videos).
In addition, insert a list on a specific page, built from the NoiseCapture raw data, that contains the following table:
Manufacturer | Device model | Device reference | Number of NoiseCapture installation | Mean value of the Gain | A distribution of the value the Gain |

The idea is to provide information for user about Gain value that are used by other for similar smartphone.

[nicolas-f]

Is the user_profile (none, novice, expert) has an impact while fetching calibration values ?

[Picaut]

Yes. Probably.
One can also consider that Gain to 0 correspond to 'No calibration' . Thus, the mean value should be calculated only on the values that are not equal to 0 (excepted if the smartphone is perfect, i.e. wit h a calibration gain equal to 0).