allow `xst package install` to fetch packages from a repository before installation

[line-o]

Enhancement

This might be handy for instances who do not have access to any package repository.
xst would act as a proxy, fetching the package then uploading and installing it in the instance that is connected.

Alternatives

Not doing implementing this feature, because it is not worth it.

[joewiz]

Could you describe the current behavior? What does xst currently treat as its package repository?

[joewiz]

Is this related to #13 ?

[line-o]

xst does not have a package repository but tells the exist-db instance it is connected to which repository to use for dependency resolution.

[line-o]

@joewiz yes, both issues are related insofar that they allow to specify a repository other than the public one on exist-db.org.
This feature here would be interesting if the instance itself cannot access any repository. Here, xst would do the package fetching and then upload the package(s) and call install-and-deploy-from-db. Naturally, you would have to care for those to be installed in the correct order, so that all dependencies are met at installation time.

[line-o]

Pretty much like the autodeploy folder works.