Handle tag information fetching cancellation gracefully

When the user "cancels" the progress dialog that appears after reading a
tag, gracefully kill the task and quit the dialog without issue.
Project cleanup

Use IntelliJ's code inspections to guide refactoring.
Change Add Tag to flow to write NFC after submit

Also, remove WriteTagActivity because it's useless.
Update dialog titles

Titles were copy-pasted and were irrelevant to their respective dialog
boxes.
Update comments