PMC not calculated when empty day

[Daniel Besse]

Example:

1. Training Wednesday and uploading activity Wednesday -> PMC set until Wednesday
2. Rest day on Thursday -> PMC not updated
3. Training Friday -> No data for Thursday => wrongly assumes 0 ATL/CTL

Solution:

1. update PMC via cron every day
2. if PMC not set for day before, find last set and update from there

[Daniel Besse]

Fill eventual gap in PMC calculation from rest day (see #42)

→ <<cset 26a682e86dea>>