Measurement logging: pre-execution hook

[MatthieuDartiailh]

The idea is to have a pre-execution hook allowing to generate a log of the run measurements. Having this mechanism in place could prove quite powerful in the future but for the first implementation I propose for most settings to be hard-coded.

• the file will be saved under the application folder (in measurement). It will be rolled monthly.
• to be both human readable and allow efficient parsing I propose to use JSON. Each measurement run would be a top level entry in the file, which should allow to append to the file without the need to fully parse it.
• the information stored will contain:
  • the measurement name, id and starting time
  • the default path of the measurement
  • the ids of the tasks used
  • the ids of the instruments used

That file can then be used to generate different kind of reports is necessary

The hook does not need a view since it is hard-coded.

@galactikvoyager @leghtas this is of interest to Erwann and will be implemented by him. Feel free to provide any feedback you may have.

[MatthieuDartiailh]

Given its general nature this hook could be added in the default ones (listed in MeasurementPlugin.default_pre_hooks.