Add bound parameters map to Query object

[harryrose]

Addresses #7687. Support for bound parameters was added in #6634. However, the golang client package was not updated to support the new behaviour. This PR extends the Query object to take a list of parameters, which are POSTed to the influxdb server when the query is executed.

• CHANGELOG.md updated (No, as it is a trivial change which doesn't affect the server)
• Rebased/mergable
• Tests pass (See below)
• Sign CLA (if not already signed)

Tests

I've added a test that the parameters are encoded, (which passes).

The following tests fail when I run go test -v ./.... However, this test is also failing with a clean check-out of the master repository, so I believe it is unrelated to this PR.

FAIL github.com/influxdata/influxdb/tsdb/engine/tsm1 21.017s

[tsm1] 2016/12/05 16:14:47 Snapshot for path /tmp/tsm497135727 written in 5.765042ms
--- FAIL: TestEngine_Backup (0.02s)
	engine_test.go:185: file name doesn't match:
			got: 000000002-000000001.tsm
			exp: /tmp/tsm497135727/000000001-000000001.tsm

[harryrose]

This is probably redundant now, as influxdata/influxdb-client#3 has an implementation.

[jsternberg]

Can you rebase this and update the changelog? That other repository isn't yet ready for primetime and it would be nice to offer bound parameters with the old API for those who want to use that.

[harryrose]

Hi. sorry it has taken me a while to get to this. I've rebased, and updated the changelog as requested.