Alpha release versioning

[FabrizioMoggio]

According to: https://wiki.camaraproject.org/display/CAM/API+versioning

the version for the Alpha should be: "x.y.z-alpha.m"

I propose this version number for the Alpha: "version: 0.2.0-alpha.1"

For the URL he Guidelines prescribe: "Example: for an alpha API version 2.y.z-alpha.1, the version in the URL is v2alpha1, e.g. {apiRoot}/qod/v2alpha1."

as a consequence:

• url: "{apiRoot}/call-forwarding-signal/v0.2alpha1"

[FabrizioMoggio]

For the Release Tag, even if they can be decoupled, I propose:

v0.2.0-alpha.1

[FabrizioMoggio]

I suggest to also create a branch named: "release-0.2.0-alpha.1"

[FabrizioMoggio]

because of: #59