Minor wording changes and a couple spelling fixes
Merge pull request #1271 from carsonmcdonald/mrbgemdocfixes

Minor wording changes and a couple spelling fixes
Describe GemBox files can be located anywhere
No need to specify empty bin list anymore(example)
do not specify implementation dependant exception class names in fiber test
install gperf to prevent accidental compile error
Merge branch 'master' of github.com:mruby/mruby
Merge pull request #1272 from kyab/absolute_path_ok_for_gembox

Describe GemBox files can be located anywhere
Merge pull request #1273 from kyab/no_bins_example

No need to specify empty bin list anymore(example)
new is removed from Integer so doesn't need to be removed again in Fixnum
bob doesn't have new so don't undef
Raise a NameError when symbol isn't found.
Add undef var test
Improve undef tests
Improve alias tests
Improve ArgumentError tests
Add assert_not_equal
Improve Array tests
Fix Array Tests
Improve BasicObject tests