The MySQL DB driver has it's own DSN parsing function. Previously we
were using the url.Parse function, but this causes problems because a
valid MySQL DSN can be an invalid http URL, namely when using some
special characters in the password.

This change uses the MySQL DB driver's builtin ParseDSN function and
applies a timeout parameter natively via that.

Another benefit of this change is that we fail earlier if given an
invalid MySQL DSN.

closes #870
closes #1842

closes #1695

closes #1439
closes #1440
closes #1441
closes #1442
closes #1443
closes #1444
closes #1445

These are useful for Percona Xtradb cluster.

closes #1437

Using root as user is a bad habit.

closes #1177

Two additional config options to reduce MySQL metrics

With:
 - gather_table_lock_waits = false
 - gather_event_waits = false

```
| wc -l
34
```

With:
 - gather_table_lock_waits = true
 - gather_event_waits = true

```
| wc -l
50040
```

closes #1148
closes #1149

closes #1136

closes #889
closes #403

	shows global variables
	shows slave statuses
	shows size and count of binary log files
	shows information_schema.processlist stats
	shows perf table stats
	shows auto increments stats from information schema
	shows perf index stats
	shows table lock waits summary by table
	shows time and operations of event waits
	shows file event statuses
	shows events statements stats from perf_schema
	shows schema statistics
	refactored plugin, provided multiple fields per insert

This will basically make the root directory a place for storing the
major telegraf interfaces, which will make telegraf's godoc looks quite
a bit nicer. And make it easier for contributors to lookup the few data
types that they actually care about.

closes #564

Closes #297

Closes #284

closes #201

Closes #138