Enumerator fixes: Kernel#to_enum and Enumerator#each

  * Implement Kernel#to_enum as an alias for #enum_for
  * Enumerator#each now accepts arguments
Triage specs in spec/filters/uncategorized.
Merge pull request #531 from mieko/categorize_specs

Triage uncategorized specs
Bump version and update the CHANGELOG
fixup! Bump version and update the CHANGELOG
Changed expect_compiled to be just a wrapper around Opal::Compiler
Compiles require into Javascript as a no-op
Added "requirable" to compiler options to mark files for future requires
Enter New Builder
Cleanup path_finder stubs
Add path_finder lint shared example
Fix requires in spec/cli
Add path_reader and hike_path_finder
Let require be compiled to js
Add require support to runtime/kernel
PathReader now raises an error on missing paths
Path finder returns nil on missing files
Initialize HikePathFinder with Opal.paths
PathFinder returns existing absolute paths
Complete the NewBuilder

- paths ending in javascript are not compiled
- wrap the compiler to gain a better api
- accept a list of already required files that won't be compiled
- add build_str to build from source/path
- replace path_finder with a path_reader