Remove deprecated methods from IRC Sent metrics
Rename IRC metrics file
[IRC] Use identities_db class property
[IRC] Fix error in queries adding missing quotes when filtering
[IRC] Fix error generating sent metric

Removes DISTINCT function from the query. All message sent to IRC
channels are unique, even when the content of the message is the
same.
[IRC] Add get_init_date() and get_end_date() methods
[IRC] Add Senders metric class

Unit tests updated
[IRC] Add trends metrics
[IRC] Add Repositories metric

Unit tests results updated to include the new metric in the JSON
files.