Implement stdin support for key add command

lib/actions/keys.coffee

@@ -39,15 +39,18 @@ exports.add = permissions.user (params) ->
 	async.waterfall [
 
 		(callback) ->
-			fs.readFile(params.path, encoding: 'utf8', callback)
+			if params.path?
+				fs.readFile(params.path, encoding: 'utf8', callback)
+			else
+				helpers.readStdin(callback)
 
-		(contents, callback) ->
-			contents = contents.trim()
+		(key, callback) ->
+			key = key.trim()
 
 			url = resin.settings.get('urls.keys')
 			data =
 				title: params.name
-				key: contents
+				key: key
 			resin.server.post(url, data, callback)
 
 	], (error) ->

lib/app.coffee

@@ -288,9 +288,20 @@ capitano.command
 	'''
 	action: actions.keys.list
 
+# TODO: Write help page for this command
 capitano.command
-	signature: 'key add <name> <path>'
+	signature: 'key add <name> [path]'
 	description: 'add a SSH key to resin.io'
+	help: '''
+		Use this command to associate a new SSH key with your account.
+
+		If `path` is omitted, the command will attempt
+		to read the SSH key from stdin.
+
+		Examples:
+			$ resin key add Main ~/.ssh/id_rsa.pub
+			$ cat ~/.ssh/id_rsa.pub | resin key add Main
+	'''
 	action: actions.keys.add
 
 capitano.command

lib/helpers/helpers.coffee

@@ -6,3 +6,21 @@ exports.isDeviceUUIDValid = (uuid, callback) ->
 		return callback?(error) if error?
 		uuidExists = _.findWhere(devices, { uuid })?
 		return callback(null, uuidExists)
+
+# TODO: Find a sane way to test streams
+exports.readStdin = (callback) ->
+	stdin = process.stdin
+
+	stdin.resume()
+	stdin.setEncoding('utf8')
+
+	result = []
+
+	stdin.on('error', callback)
+
+	stdin.on 'data', (chunk) ->
+		result.push(chunk)
+
+	stdin.on 'end', ->
+		result = result.join()
+		return callback(null, result)