v0.4.16

Changelog

0fe074b Add goroutines sync, to avoid data race (TestStart test fails randomly).
540778e Add handling of corner cases when calculating WAL archiving lag.
d5931fa Add metric about wal/log directory files. Replace postgres_directory_size_bytes with set of postgres_*_directory_bytes.
00bf838 Add metrics from '/proc/vmstat'.
d5a8cb3 Add pgbouncer client connections metric.
09513d8 Add support of pg_stat_archiver.
0d8eac7 Add xid limits metric.
0d71956 Adjust exit messages; update project URL in '/' http page.
8401cf7 Doc: add notes related to tracking sensitive information. Fix env vars used at bootstrap.
220d4d8 Doc: fix download links.
a030083 Fix string assert in test.
c5a3907 Fix tests.
2f10424 Fix tests.
ef45e50 Fix tests.
98a1f5d Merge remote-tracking branch 'origin/master'
6d2c55a Postgres storage metric changes: add per-tablespace temp files metric; always return temp files in-flight metrics; minor edits.
d06ad6f Remove _total suffix from database size metric (because it is gauge).
6936940 Reorder labels in pgbouncer pool metrics.
fa2dff6 Update issue templates
f8461d8 Use singular value in label of diskstats metrics
b9094d6 Use unsigned type for BlockSize.