Showing name and URL for solved challenges (#90).
Cleaning up .gitignore
Adjustments according to pep8.
Merge remote-tracking branch 'upstream/master'
Fixing indentation according to pep8 (#90)
Describing DB problems troubleshooting,

minor clarifications to other parts of readme,
fixing a minor inaccuracy in app.yaml.
Fixing newlines in markdown.
Further fixing newlines in markdown.
Merge pull request #104 from egor83/db_debugging

DB debugging description