Updated dependency on major 1 of greentea-client

[bogdanm]

No description provided.

[bogdanm]

Major version 1 of greentea-client might not be published yet, but this change is backwards compatible.
The intention is to release a new minor version of this module once this PR is merged.
@0xc0170 @bremoran

[bremoran]

-1. This should be a test dependency. Fixing this problem will fix the failures in other modules.

[bogdanm]

This one is a regular dependency: https://github.com/ARMmbed/mbed-drivers/blob/master/source/retarget.cpp#L74

[bremoran]

https://github.com/ARMmbed/mbed-drivers/blob/master/source/retarget.cpp#L73 ensures that it is only used if the module is present in the build. This is still a test dependency.

[bogdanm]

I'm sorry, but I believe it's too risky to make this into a test dependency right now (in the context of the release), because I don't know what could break if we do so. Feel free to open a separate issue for this.

[bogdanm]

Merging as it is for now. @bremoran opened #183 to track this.