Plugin is declared incompatible with strophejs 2.x

[tari]

strophejs 2.0.0 was just released, which increments the major version but doesn't appear to contain any API changes that would break this plugin. Since this currently declares a peer dependency on strophe.js ^1, dependency resolution does not permit upgrade of strophe.js.

I think the most reasonable solution is to update the peer dependency to be ^1.2.12 || ^2.0.0 to accept new 2.x versions of strophe while continuing to assume that post-2.x versions might break the plugin (requiring updates for any future major versions). Alternately, use >=1.2.12 to be optimistic that no future version of Strophe will break this plugin.

[jcbrand]

Hi @tari, can you please make a PR with the proposed change? The plugins are largely unmaintained currently.

[tari]

The dependency is updated with #6, but it would be nice to get a new version on npm so there's a release including the fixed dependency.