Add docker containers to test services.

This commit initializes the needed services which are not mocked
so tests can be executed in any environment with docker.

Some default modifications (i.e: connection strings) were also made to
current tests to accomodate them for this setup.

A docker-compose.yml file is provided with all the necessary parameters
for this services to be initialized. Future services can be added
easily by extending this configuration file

In addition a makefile has been introduced to simplify command execution

plugins/mysql/mysql_test.go

@@ -11,7 +11,7 @@ import (
 
 func TestMysqlGeneratesMetrics(t *testing.T) {
 	m := &Mysql{
-		Servers: []string{""},
+		Servers: []string{"root@tcp(localhost:3306)/"},
 	}
 
 	var acc testutil.Accumulator
@@ -53,7 +53,9 @@ func TestMysqlGeneratesMetrics(t *testing.T) {
 }
 
 func TestMysqlDefaultsToLocal(t *testing.T) {
-	m := &Mysql{}
+	m := &Mysql{
+		Servers: []string{"root@tcp(localhost:3306)/"},
+	}
 
 	var acc testutil.Accumulator