Created new WelcomeActivity

It seems to work as intended right up until you actually try to post.  I
think the issue is that I changed the password field to a passwordText
field in the prefs.xml, prefactivity, and welcomeactivity...
updating Welcome Activity to check not only for existing of shared preference, but also for blankness of shared preference value.  adding API Root to shared preference value check and input.  moving shared preference keys to strings.xml to reference from both Java and XML