Support abbr options and refine the code

DESC:
[Feature]
1. Support abbr options and refine the code
(1). Support abbr options, for example: :seed -> :s
(2). Refine the code, use block to reduce the duplicated codes.
(3). Update the README, use the new hash style and focus on the format
feature.
(4). Discard the "get" and "strf" interface, use "gen" instead.
(5). Add check option feature.
Merge branch 'develop' of github.com:sibevin/random_token into develop

Conflicts:
	lib/random_token.rb
Add version badge in README

DESC:
[Change]
1. Add version badge in README
Modify tests to support the rubinius regex

DESC:
[Change]
1. Modify tests to support the rubinius regex
Modify tests to support the rubinius regex(2)

DESC:
[Change]
1. Modify tests to support the rubinius regex
Change hash style to 1.8.7 in tests

DESC:
[Change]
1. Change hash style to 1.8.7 in tests
For testing 1.8.7
Add travis build badge in README

DESC:
[Change]
1. Add travis build badge in README
Refine README

DESC:
[Change]
1. Refine README
Update version to 1.0.1

DESC:
[Release]
1. Update version to 1.0.1
Only refine the code, no interface is changed.