Change pop up browser alerts for modal dialogs.

[FdezAriasSara]

Create a base react component for a modal dialog so it can be used instead of alerts
I will also use it for things like allowing the user to choose which pod to create the folder of lomap into.
or to ask for consent to create the folder itself in order to enter the app.

alert example:(what we have now)

what I will try to do :

[FdezAriasSara]

In case a user logs in and his/her web id has many pods associated, we will have to handle if we allow him/her to have lomap folders in more than one pod.

That could be done with modal dialogs DropDownLists where we allow the user to choose the pod.

For the moment i will try to keep it simple., by just allowing the user to choose the pod his/her first lomap folder after not finding one in all pods