[Ivan Diaz] - Minor i18n key updates

src/app/main/main-layout-header.js

@@ -10,7 +10,7 @@ var MainLayoutHeader = React.createClass({
             <div className="main-layout-header">
                 <div className="main-layout-header--login-links">
                    <Button type="clean" route={{to:'/app'}}>{i18n('LOG_IN')}</Button>
-                   <Button type="clean" route={{to:'/app/signup'}}>Sign up</Button>
+                   <Button type="clean" route={{to:'/app/signup'}}>{i18n('SIGN_UP')}</Button>
                    <Button type="clean" onClick={function () {CommonActions.changeLanguage('es');}}>Spanish</Button>
                    <Button type="clean" onClick={function () {CommonActions.changeLanguage('en');}}>English</Button>
                 </div>

src/data/i18n-keys.js

@@ -1,4 +1,5 @@
 export default {
     'SUBMIT': ['Submit', 'Enviar'],
-    'LOG_IN': ['Log is', 'Logearse']
+    'LOG_IN': ['Log in', 'Ingresar'],
+    'SIGN_UP': ['Sign up', 'Registrarse']
 };