vendor: update all dependencies

* Update all dependencies
  * Remove all `[[constraint]]` from Gopkg.toml
  * Add in the minimum number of `[[override]]` to build
  * Remove go get of github.com/inconshreveable/mousetrap as it is vendored
  * Update docs with new policy on constraints

vendor/github.com/aws/aws-sdk-go/aws/endpoints/decode.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"os"
 
 	"github.com/aws/aws-sdk-go/aws/awserr"
 )
@@ -85,8 +84,6 @@ func decodeV3Endpoints(modelDef modelDefinition, opts DecodeModelOptions) (Resol
 		custAddEC2Metadata(p)
 		custAddS3DualStack(p)
 		custRmIotDataService(p)
-
-		custFixRuntimeSagemakerSigningName(p)
 	}
 
 	return ps, nil
@@ -125,26 +122,6 @@ func custRmIotDataService(p *partition) {
 	delete(p.Services, "data.iot")
 }
 
-func custFixRuntimeSagemakerSigningName(p *partition) {
-	// Workaround for aws/aws-sdk-go#1836
-
-	s, ok := p.Services["runtime.sagemaker"]
-	if !ok {
-		return
-	}
-
-	if len(s.Defaults.CredentialScope.Service) != 0 {
-		fmt.Fprintf(os.Stderr, "runtime.sagemaker signing name already set, ignoring override.\n")
-		// If the value is already set don't override
-		return
-	}
-
-	s.Defaults.CredentialScope.Service = "sagemaker"
-	fmt.Fprintf(os.Stderr, "sagemaker signing name not set, overriding.\n")
-
-	p.Services["runtime.sagemaker"] = s
-}
-
 type decodeModelError struct {
 	awsError
 }