add 'alias' command for querying and setting the alias (#126)

* add 'alias' command for querying and setting the alias

* calculate coverage only on library files, e.g., ignoring cli and test files

* remove py34 and add py37

* readd py33, remove it from travis as it seems to be a travis limitation only

* use xenial dist for travis, regular does not support py37..

pyHS100/cli.py

@@ -111,6 +111,18 @@ def state(ctx, dev):
     ctx.invoke(emeter)
 
 
+@cli.command()
+@pass_dev
+@click.argument('new_alias', required=False, default=None)
+def alias(dev, new_alias):
+    """Get or set the device alias."""
+    if new_alias is not None:
+        click.echo("Setting alias to %s" % new_alias)
+        dev.alias = new_alias
+
+    click.echo("Alias: %s" % dev.alias)
+
+
 @cli.command()
 @pass_dev
 @click.option('--year', type=Datetime(format='%Y'),