Demisto-sdk

* Fixed an issue where demisto-sdk **validate** failed on modified scripts without error message.

* Fixed an issue with docker tag validation for integrations.
* Restructured repo source code.

* Saved failing unit tests as a file.
* Fixed an issue where "_test" file for scripts/integrations created using **init** would import the "HelloWorld" templates.
* Fixed an issue in demisto-sdk **validate** - was failing on backward compatiblity check
* Fixed an issue in demisto-sdk **secrets** - empty line in .secrets-ignore always made the secrets check to pass
* Added validation for docker image inside integrations and scripts.
* Added --use-git flag to **format** command to format all changed files.
* Fixed an issue where **validate** did not fail on dockerimage changes with bc check.
* Added new flag **--ignore-entropy** to demisto-sdk **secrets**, this will allow skip entropy secrets check.
* Added --outfile to **lint** to allow saving failed packages to a file.

* Added backwards compatibility break error message.
* Added schema for incident types.
* Added **additionalinfo** field to as an available field for integration configuration.
* Added pack parameter for **init**.
* Fixed an issue where error would appear if name parameter is not set in **init**.

* Fixed the handling of classifier files in **validate**.

* Fixed the handling of newly created reputation files in **validate**.
* Added an option to perform **validate** on a specific file.