frontend: move all css in 'zsd.css'
update README
frontend: refactoring
frontend: new utility functions: whenIsViewable / whenIsComparable
backend: remove obsolete 'max-file-size' flag
frontend: show warnings
  * listen on 'zsd:warnings' events
  * show warnings in user interface
frontend: prefix all events with 'zsd'
   * own events should be in a seperated name space
frontend: execute default action on file selection
  * default action: view file content
  * configurable per prog args
build: update git submodule on build
frontend: syntax highlight on view file
frontend: prefix all directives with 'zsd'
   * own directives should be in a seperated name space
frontend: js code as angular modules
  * its the preferred method
backend: refactor rest backend
  * code cleanup
update README
add LICENSE
implement 'restore file'
  * restore file from a given snapshot
  * renames the actual file to <FILENAME>_<TIMESTAMP>
fix go tests
Merge branch 'master' into develop