Implement initial twitterstats module

* Create module skeleton based off of the existing twitter module
  * Strip out unused pieces and try to make it as minimal as possible
 * Implement settings parsing, converting the untyped `screenNames` slice into an slice of strings
 * Implement initial minimal display, showing a table with all usernames and their follower count + # of tweets (using dummy metrics for now)

modules/twitterstats/settings.go

@@ -0,0 +1,39 @@
+package twitterstats
+
+import (
+	"os"
+
+	"github.com/olebedev/config"
+	"github.com/wtfutil/wtf/cfg"
+)
+
+const (
+	defaultFocusable = true
+	defaultTitle     = "Twitter Stats"
+)
+
+type Settings struct {
+	common *cfg.Common
+
+	consumerKey       string
+	consumerSecret    string
+	accessToken       string
+	accessTokenSecret string
+
+	screenNames []interface{}
+}
+
+func NewSettingsFromYAML(name string, ymlConfig *config.Config, globalConfig *config.Config) *Settings {
+	settings := Settings{
+		common: cfg.NewCommonSettingsFromModule(name, defaultTitle, defaultFocusable, ymlConfig, globalConfig),
+
+		consumerKey:       ymlConfig.UString("consumerKey", os.Getenv("WTF_TWITTER_CONSUMER_KEY")),
+		consumerSecret:    ymlConfig.UString("consumerSecret", os.Getenv("WTF_TWITTER_CONSUMER_SECRET")),
+		accessToken:       ymlConfig.UString("accessToken", os.Getenv("WTF_TWITTER_ACCESS_TOKEN")),
+		accessTokenSecret: ymlConfig.UString("accessTokenSecret", os.Getenv("WTF_TWITTER_ACCESS_TOKEN_SECRET")),
+
+		screenNames: ymlConfig.UList("screenNames"),
+	}
+
+	return &settings
+}