Skip nodes functionality for Package and Network modules

Added to main entrypoint
- Skip nodes using simple argument with '*' as a trailing wildcard
- Skip nodes using file list

Usability improovement
- Node list preview in status line
- Node stats alignment in net report

Minor fixes:
- Python version detection (3.5+)
- Node counter for each status
- Proper node skip handling

Change-Id: I086ef501bc06f0e739df25349257f1c63a2e2fcf
Related-PROD: PROD-35009
diff --git a/cfg_checker/modules/packages/__init__.py b/cfg_checker/modules/packages/__init__.py
index 41dfca1..2d0cc79 100644
--- a/cfg_checker/modules/packages/__init__.py
+++ b/cfg_checker/modules/packages/__init__.py
@@ -112,9 +112,12 @@
         _kw = [args.exclude_keywords]
 
     # init connection to salt and collect minion data
+    _skip, _skip_file = args_utils.get_skip_args(args)
     pChecker = checker.CloudPackageChecker(
         force_tag=args.force_tag,
-        exclude_keywords=_kw
+        exclude_keywords=_kw,
+        skip_list=_skip,
+        skip_list_file=_skip_file
     )
     # collect data on installed packages
     pChecker.collect_installed_packages()
diff --git a/cfg_checker/modules/packages/checker.py b/cfg_checker/modules/packages/checker.py
index 8f30f3c..fb02db2 100644
--- a/cfg_checker/modules/packages/checker.py
+++ b/cfg_checker/modules/packages/checker.py
@@ -12,10 +12,19 @@
 
 
 class CloudPackageChecker(object):
-    def __init__(self, force_tag=None, exclude_keywords=[]):
+    def __init__(
+        self,
+        force_tag=None,
+        exclude_keywords=[],
+        skip_list=None,
+        skip_list_file=None
+    ):
         # Init salt master info
         if not salt_master.nodes:
-            salt_master.nodes = salt_master.get_nodes()
+            salt_master.nodes = salt_master.get_nodes(
+                skip_list=skip_list,
+                skip_list_file=skip_list_file
+            )
 
         # check that this env tag is present in Manager
         self.rm = RepoManager()
@@ -57,6 +66,7 @@
         _data['status_err'] = const.VERSION_ERR
         _data['status_warn'] = const.VERSION_WARN
         _data['status_down'] = const.VERSION_DOWN
+        _data['status_skip'] = const.VERSION_NA
 
         # Presort packages
         _data['critical'] = {}