closes #934

closes #888

closes #876

closes #927

fixes #873

closes #906

closes #841

fixes #907

closes #656

closes #848

closes #898

it usually connotes a single value type metric, appending just clutters

closes #793

if i understand the prometheus data model correctly, the current output
for this plugin is unusable

prometheus only accepts a single value per measurement. prior to this change, the range loop
causes a measurement to end up w/ a random value

for instance:

net,dc=sjc1,grp_dashboard=1,grp_home=1,grp_hwy_fetcher=1,grp_web_admin=1,host=sjc1-b4-8,hw=app,interface=docker0,state=live
bytes_recv=477596i,bytes_sent=152963303i,drop_in=0i,drop_out=0i,err_in=0i,err_out=0i,packets_recv=7231i,packets_sent=11460i
1457121990003778992

this 'net' measurent  would have all it's tags copied to prometheus
labels, but any of 152963303, or 0, or 7231 as a value for
'net' depending on which field is last in the map iteration

this change expands the fields into new measurements by appending
the field name to the influxdb measurement name.

ie, the above example results with 'net' dropped and new measurements
to take it's place:
	net_bytes_recv
	net_bytes_sent
	net_drop_in
	net_err_in
	net_packets_recv
	net_packets_sent

i hope this can be merged, i love telegraf's composability of tags and
filtering

closes #762

closes #789

sanitize known issue characters from graphite tag name

closes #866
closes #482

Proper terminology and case. Exmaples for tags. Example output.

Make `go vet` happy.

replace @ character with - for librato

closes #844

This plugin is intended to add an extended support of Postgresql
compared to the legacy postgres plugin.

Basically, the plugin don’t have any metrics defined and it’s up to the
user to define it in the telegraph.conf (as a toml structure).

Each query can have it’s specific tags, and can be written specifically
using a where clause in order to eventually filter per database name.

To be more generic, a minimum postgresql version  has been defined per
query in case you have 2 different version of Postgresql running on the
same host.

This way, after a reload, the stats wont restart again at least for the
counter type.

closes #887