AWS_PROFILE Env Var Support (#15)

* Added AWS_PROFLE and shared cred

Following convention, if the command line arguments does not specify
a profile, we check the AWS_PROFILE. The sdk session options is also
initialised with SharedConfigEnable to support shared configurations
from the (~/.aws/config). https://github.com/aws/aws-sdk-go#configuring-credentials

* AWS_PROFILE and shared cred

Following convention, if the command line arguments does not specify
a profile, we check the AWS_PROFILE. The sdk session options is also
initialised with SharedConfigEnable to support shared configurations
from the (~/.aws/config). https://github.com/aws/aws-sdk-go#configuring-credentials

* Removing AWS_PROFILE lookup in fav sharedConfigEnabled

By setting up the sharedConfigState to enabled the SDK does take care
of the AWS_PROFILE population: https://docs.aws.amazon.com/sdk-for-go/api/aws/session/#SharedConfigState

* removing unused const AWS_PROFILE

Author: ruecarlo

cmd/main.go

@@ -270,7 +270,7 @@ func getOutputFn(outputFlag *string, currentFn selector.InstanceTypesOutputFn) s
 }
 
 func getRegionAndProfileAWSSession(regionName *string, profileName *string) (*session.Session, error) {
-	sessOpts := session.Options{}
+	sessOpts := session.Options{SharedConfigState: session.SharedConfigEnable}
 	if regionName != nil {
 		sessOpts.Config.Region = regionName
 	}