Add support for SamplesheetV2 and MiSeq sequencer

[ESapenaVentura]

This PR:

• Adds support for SampleSheetV2 (As long as the old [Data] header is present with the new header [CustomCustomer_Data]) ( wetlab/utils/samplesheet.py)
• Adds support for new sequencer addition (Fixed a bug in core/models.py)
• Adds support for MiSeq_100 XML completion tag AND support for MiSeq_100 timestamps AND fixes error in setting cancelled statuses in sequencer_run_is_completed (wetlab/utils/crontab_process.py)
• Added new tags in config to support MiSeq_100 (wetlab/config.py)
• Adds new possible value custom_description (wetlab/config.py)

Also, completely re-factors samplesheet - functionality should remain (mostly) intact