preview images
fix menthod name + jslint
fix DocumentCommandHandlers tests
- add test case to validate the EditorManager APIs getActiveEditor, getCurrentFullEditor and getFocusedEditor return null after opening an image
- add test case to validate the EditorManager APIs getActiveEditor, getCurrentFullEditor and getFocusedEditor return en editor after opening a text file
- resolve promise on opening image
- update test case to expect no current document when image is open
fix bug found during test development: fire currentDocumentChanged when image is replacing a text document
- add unit test for prettyPrintBytes (+13 squashed commits)
- add test case for clearCurrentlyViewedFile
- add test case for getCurrentlyViewedFile and setCurrentlyViewedFile
- add test case for clearCurrentDocument
- add DocumentManager integration tests
- add test cases to verify that currentDocumentChange and activeEditorChange events are fired correctly
- fix minor nits: update jsdoc + format + copyrights + style +  quotes + comments, remove unused vars
- refactored & simplified some code around removing custom viewers per suggestion by @RaymonLim
minor nit + typo
fixes for various nits found by @RaymondLim in code review.
Merge branch 'master' into couzteau/preview-images-review

Conflicts resolved
	test/UnitTestSuite.js
fix test case - per @RamondLim. Thanks for the extra pointer.
Peter's review feedback
-  FileViewController now listens to EditorManager's currentlyViewedFileChange event instead DocumentManager's currentDocumntChange event. This removes the need  to update the EditorManager's currentlyViewedFile property when setting the current document, i.e. by using the FILE_OPEN command.DocumentManager gets smarter about sending currentDocumntChange events, i.e. it won't send its clear method is called and no document has been current.
- rename CurrentlyViewedFile to CurrentlyViewedPath
- remove obsolete exports
- remove         _$previousCustomViewer
- jquery prefixes
-  no dependency on ImageViewer in Editor Manaeger
 Changes in response to review comments from @peterflynn and @redmunds
reuse existing images
- do also set file  t file open default path when opening an image
- quotes in StringUtils
Merge pull request #5530 from adobe/couzteau/preview-images-review

preview images - updated