Refactoring "AnnotationManager::applyConstrains" method to increase clarity

- also fixing annotation inheritance test (typo error)
Unsure that returned annotation indexes are sequential
Merge pull request #72 from php-annotations/sequentinal-index-in-returned-annotation-array

Unsure that returned annotation indexes are sequential
Removing redundant code in "getUsage" method

Code, that locates parent `@usage` annotation is removed in `getUsage` method in favor code in `getAnnotations` method, that recursively obtains all annotations including ones from parent classes.
Merge pull request #70 from php-annotations/remove-redundant-usage-annotation-handling

Removing redundant code in "getUsage" method
Don't allow getting annotation from non-existing class properties
Merge pull request #69 from php-annotations/annotation-constrain-apply-refactoring

Refactoring "AnnotationManager::applyConstrains" method
Merge pull request #79 from php-annotations/74-verify-that-property-exists-before-reading-it-s-annotations

Don't allow getting annotation from non-existing class properties
Getting warning about 0 array index instead of annotation exception