gofmt load_container_filters.go

removed the environment variable for container label filters

Added the --app.container-label-filter command line argument, and load_container_filters.go now uses the results from that

Changed init() to InitializeTopologies()

Changed init() to InitializeTopologies() so that it can be called after the container filters are loaded from the command line argument. init() executes before main() in prog/main.go, so the flag parsing isn't finished before init() is called

Applied lint fixes

fixed lint issues

brought back the init function for api_topologies.go

Addressed many of the PR comments, except escaping colons

Renamed IsDesired to HasLabel in render/filters.go

Allows for the user to escape colons

added registry function for modifying the container filters

created a separate function that parses the container filter flags

simplified registry.addContainerFilters()

addressed review comments

switched API Topology Description IDs to constants

addressed review comments

joined constants

added test functions

addressed most of the review comments

Changed containerLabelFilters to an array of APItopologyOptions, placing the parsing in the Set() function. Removed parsing from HasLabel in render/filters.go

refactored code

added test that applies to the container filtering by labels

applied golint

made Registry items private and added a MakeRegistry() function

fixed usage of topologyRegistry.RendererForTopology

Added container label filters by exclusion

minor update to report_fixture

Modified container labels test to use existing report

I added labels to the existing containers in the fixed report for testing.

refactored code

refactored code

further code refactoring

addressed @ijsnellf's review comments

unexported Registry, and reduced duplicate code

addressed @ijsnellf's review comments

Addressed review comments

Addressed final review comments