Remove docker-machine/boot2docker dependencies & references

CONTRIBUTING.md

@@ -114,7 +114,7 @@ creating the `Parser` object.
 You should also add the following to your SampleConfig() return:
 
 ```toml
-  ## Data format to consume. 
+  ## Data format to consume.
   ## Each data format has it's own unique set of configuration options, read
   ## more about them here:
   ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
@@ -244,7 +244,7 @@ instantiating and creating the `Serializer` object.
 You should also add the following to your SampleConfig() return:
 
 ```toml
-  ## Data format to output. 
+  ## Data format to output.
   ## Each data format has it's own unique set of configuration options, read
   ## more about them here:
   ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_OUTPUT.md
@@ -290,10 +290,6 @@ To execute Telegraf tests follow these simple steps:
 instructions
 - execute `make test`
 
-**OSX users**: you will need to install `boot2docker` or `docker-machine`.
-The Makefile will assume that you have a `docker-machine` box called `default` to
-get the IP address.
-
 ### Unit test troubleshooting
 
 Try cleaning up your test environment by executing `make docker-kill` and