Customize alerts table

[bzurkowski]

Customize the alerts table with the following items:

• Remove ID column
• Add columns: severity, timestamp, origin, name, message (in that order)
• Add badges for severity
• Add column sorting
• Set default table sorting by alert severity
• Add severity and origin selector
• Add searching columns by phrase (generic)
• Add pagination with selectable number of rows

[bzurkowski]

Closed by #62.