Merge pull request #6 from mkreyman/65851750_about_hashes_master

Fixed about_hashes.rb to pass all tests

[Delivers #65851750]
Merge pull request #9 from mkreyman/65851756_about_regular_expressions_master

about regular expressions master

[Delivers #65851756]
Merge pull request #10 from mkreyman/65851758_about_methods_master

about methods master

[Delivers #65851758]
Added keyword_arguments
Merge pull request #11 from mkreyman/65851762_about_constants_master

about constants master

[Delivers #65851762]
Merge pull request #12 from mkreyman/65851764_about_control_statements_master

about control statements master

[Delivers #65851764]
Fixed about_true_and_false.rb to pass all tests

Learned about/that:
* true is treated as true,
* and false is treated as false,
* nil is also treated as false,
* everything else is treated as true.

[#65851766]