Improve error reporting from verify_files

Make it similar to what verify_env already does, so that
we tell people exactly which path was a problem.  I hit this
while running salt-master in a non-standard configuration, and
the change makes it easier to hunt down which path is wrong
in a config.
ddns: ensure name is str
Merge pull request #8181 from mgwilliams/ddns

ddns: ensure name is str
libevent-dev required to pip install gevent
Merge pull request #8182 from bretep/patch-1

libevent-dev required to pip install gevent
Fix the Halite tutorial code blocks under configuration.
Merge pull request #8183 from s0undt3ch/develop

Fix the Halite tutorial code blocks under configuration.
Ammended iptables check if statement was mis-tabbed.
Fix for managing debian repos with trailing slashes in the URI

This commit modifies apt.py's expand_repo_def and list_repos (as well as
get_repo, as it uses list_repos) functions to strip the trailing slash.
This allows for repo definitions to be created with trailing slashes,
and for a trailing slash to not result in a failure to match a repo.

Additionally, this commit has fixes for generic "raise Exception" usage,
instead using salt.exceptions.CommandExecutionError as it avoids
tracebacks in the CLI output.

Finally, some manual quoting has been converted to using raw strings.
Make newly-added repo available to pkg states

If a package is added using a pkgrepo.managed state, and a pkg.installed
state needs access to this newly-added repo, it will not be able to find
the package since the pkg.refresh_db happens in the call to pkg.install
(just prior to the package installation), and not when the package
targets are initially looked for. This commit adds a pkg.refresh_db
before the targets are checked, and then supresses the refresh_db when
the package is actually installed (because at that point, it would be
redundant).
Merge pull request #8185 from c-cooperjones/develop

Ammended iptables check if statement was mis-tabbed.
Merge pull request #8186 from terminalmage/issue7696

Fix for managing debian repos with trailing slashes in the URI
Integration tests for #8174, #7905 & #8114: sls syntax errors
Merge remote-tracking branch 'upstream/develop' into develop
Use the nested outputter for changes in highstate display
Allow a string definition to be passed into get_colors

This allows for an outputter to send a washout color for all output
Pass in CYAN to the nested outputter for changes output
Allow a nested default to be passed in opts to start the

nested outputter in a deeper structure
Pass in a starting indent for the nested outputter
Merge pull request #8195 from regilero/develop

Integration tests for  sls syntax errors