fix /models/apis/Greengrass dep case sensitivity

[lokesh-shekar]

Version of AWS SDK for Go?

version = "1.10.44". This would apply to all versions which had the #1538 changes merged.

Version of Go (go version)?

go version go1.9 darwin/amd64

What issue did you see?

• We use https://github.com/golang/dep for dependency management.

• Things were working fine until the above mentioned PR was merged

• 'dep ensure' throws the below error.
  (59/59) Failed to write github.com/aws/aws-sdk-go@v1.10.49
  grouped write of manifest, lock and vendor: error while writing out vendor tree: failed to write dep tree: failed to export github.com/aws/aws-sdk-go: : exit status 128

• On trying to debug:
  $ cd $GOPATH/pkg/dep/sources/https---git.luolix.top-aws-aws--sdk--go/
  $ git status
  HEAD detached at 599f09b
  Changes not staged for commit:
  (use "git add ..." to update what will be committed)
  (use "git checkout -- ..." to discard changes in working directory)

  modified: models/apis/Greengrass/2017-06-07/api-2.json
  modified: models/apis/Greengrass/2017-06-07/docs-2.json

no changes added to commit (use "git add" and/or "git commit -a")

• Since there already exists models/apis/greengrass (lowercase). This breaks many package managers, leading to conflict.

Steps to reproduce

• Have a go code importing github.com/aws/aws-sdk-go
• Use dep as your package manager
• Run 'dep ensure' command and you hit the above error.

[ilovezfs]

This breaks with glide install too, when attempting to build terragrunt, which depends on aws-sdk-go. See gruntwork-io/terragrunt#296.

[jasdel]

Thanks for reporting this issue let's use #1540 to tack this issue.