Merge pull request #16 from krtx/master

Add account management
reject -> reject!
Merge pull request #21 from krtx/master

Fixed a bug.
Use zip library to compress files and patterns to specify files
Merge pull request #22 from OKU1987/oku/gem

Use zip library to compress files and patterns to specify files
Change the ways to tokenize and to group exercises

Only exercises which share the same prefix have parent-child relations
Merge pull request #17 from OKU1987/oku/grouping

Change the ways to tokenize and group exercises
Validates the input in register.cgi.
Add 'mail' gem to Gemfile.
Merge pull request #23 from chiro/validate-input

Validates the input in register.cgi.
Merge pull request #24 from chiro/use-bundler

Add 'mail' gem to Gemfile.
Implement Report::Exercise::Token#start_with?.
Add more tests for Report::Exercise.

- Underscore is not the separator.
- New grouping rule.
Merge pull request #25 from chiro/compat-with-string

Implement Report::Exercise::Token#start_with?.
Modified the login validation in register.cgi.