fixes #497 and #524

[ArtPoon]

• use Math.log10 transform on predicted numbers of infections by lineage to improve distribution for colour palette
• added predicted number of infections (tip.infections) to lineage CSV output
• tweaked infections legend label in all four languages

[GopiGugan]

Checking the following:

• [x] Search
  • [x] Search by accession number
  • [x] Search by lineage
  • [x] Search by country
  • [x] Search by country (with date filter)
• [x] Tree filtering
• [x] Download Time-scaled tree (nwk)
• [x] Download Time-scaled tree (csv)
• [x] Download Beadplot (svg)
• [x] Download Beadplot (nwk)
• [x] Download mutation list (csv)
• [x] Beadplot cutoff slider
• [x] Expanding Beadplot
• [x] Translated pages
• [x] Changing the colour of the tree based on divergence, collection date, etc.
• [x] Left/Right arrow key to move between beads
• [x] Tooltips
• [x] Countries/Samples/Mutations tabs are populating the correct information
• [x] Build front-end database without issues
• [ ] Port front-end change to epicov branch