feat(db): store metadata as a file (aquasecurity#464)

* refactor: wrap errors

* feat(db): add the metadata file

* test(db): re-generate mocks

* fix(app): read metadata from the file in showVersion

* fix: open the database after downloading it

* fix(operation): use UpdateMetadata

* chore(mod): update dependency

* test(integration): fix tests

* fix(conf): rename TRIVY_NONSSL to TRIVY_NON_SSL

Fix CircleCI example in README.md (aquasecurity#451)

After trying to run trivy using CircleCI based on the sample configuration and failing, I want to suggest the following updates:

* `docker:18.09-git` no longer exists and causes workflow to fail, replaced with `stable-git` instead.
* added  `setup_remote_docker` or else the docker commands fail in the rest of the execution, as per https://circleci.com/docs/2.0/building-docker-images/#overview

Co-authored-by: Teppei Fukuda <knqyf263@gmail.com>

app: Fix a few edge cases with version flag (aquasecurity#443)

* app: Show just version if DB is missing

Signed-off-by: Simarpreet Singh <simar@linux.com>

* app: Dont panic if cache-dir is bogus

Signed-off-by: Simarpreet Singh <simar@linux.com>

* app: DRY up logic for showVersion

Signed-off-by: Simarpreet Singh <simar@linux.com>

fix(rpm): make it possible to scan non-RHEL images without rpm (aquas…

…ecurity#429)

fix(token): use the credential from enviroment variable (aquasecurity…

…#427)

chore(goreleaser): drop BSD support temporarily (aquasecurity#424)

fix(client): add image name and build time (aquasecurity#402)

* WIP: Add imageName and BuildTime for Remote detector

Signed-off-by: Simarpreet Singh <simar@linux.com>

* wip

Signed-off-by: Simarpreet Singh <simar@linux.com>

* change name from build_time to created

* remove an unused function

* fix(library): add image_name and created_at

* fix(ospkg): add image_name and created_at

* fix(scan): add image_name and created_at

* fix(library): remove unused param

Co-authored-by: Simarpreet Singh <simar@linux.com>

chore: add install script (aquasecurity#370)

* chore: add install script

* installer: change perms to include +x

Signed-off-by: Simarpreet Singh <simar@linux.com>

Co-authored-by: Simarpreet Singh <simar@linux.com>

Fix inifinite loop when resolving dependencies of packages in Alpine (a…

…quasecurity#364)

* Change fanal ref

* Fix Inifinite loop when resolving dependencies of packages in Alpine

chore(dep): update (aquasecurity#357)