load_gen: Supporting loading of load_gen via loader.

Currently all tools are loaded via loader utility, except load_gen.
Load_gens were loaded directly through component_factory.
This patch adds support to load load_gens through loader utility.

The changes are as follows:
1. Configuration changes:The common.conf include configuration of
   directory. testcases.conf includes changes to load configuration,
   where tool is no more part of the load-configuration. The
   custom.conf has configuration of LOADGEN to be used - this configuration
   replaces the earlier 'tool' configuration parameter.
2. loader_utility_changes:  In loader.py, loadgen_loader is
   defined, which is used in new get_loadgen function.
3. component_factory changes: in create_loadgen, similar
   to other tools, the function just retuns the object of loadgen_class.
4. Renaming of Dummy load_gen: Loader fails to load properly a dummy
   loadgen due to name-clash with dummy in pkt_gen. To avoid this name clash
   dummy is renamed to dummyloadgen.
5. testcase changes: create_loadgen is now called with output of
   loader's get_loadgen_class.
6. Fixed Pylint Errors and extra-space at the end.
7. Included CLI options support for --loadgen and --list-loadgens.
   Thanks to Martin K.
8. Added the missing loadgen parameter in testcases.conf.
9. Fixed the missing comma error.
10. Added CI change in build-vsperf.sh
11. Fixed configuration reading in stress/stress.py

JIRA: VSPERF-533

Change-Id: I3fbb259618825a12fef55320a748a4f02509190b
Signed-off-by: Sridhar K. N. Rao <sridhar.rao@spirent.com>
Signed-off-by: Martin Klozik <martinx.klozik@intel.com>

3 files changed, 4 insertions, 2 deletions

diff --git a/tools/load_gen/dummy/__init__.py b/tools/load_gen/dummyloadgen/__init__.py
index 834e9f63..834e9f63 100644
--- a/tools/load_gen/dummy/__init__.py
+++ b/tools/load_gen/dummyloadgen/__init__.py
diff --git a/tools/load_gen/dummy/dummy.py b/tools/load_gen/dummyloadgen/dummyloadgen.py
index 91bef4fa..91bef4fa 100644
--- a/tools/load_gen/dummy/dummy.py
+++ b/tools/load_gen/dummyloadgen/dummyloadgen.py
diff --git a/tools/load_gen/stress/stress.py b/tools/load_gen/stress/stress.py
index 4c69a170..0790d47c 100644
--- a/tools/load_gen/stress/stress.py
+++ b/tools/load_gen/stress/stress.py
@@ -52,8 +52,10 @@ class Stress(ILoadGenerator):
             return
 
         # check if load tool binary is available
-        if not ('tool' in stress_config) or subprocess.call("which " + stress_config['tool'], shell=True) > 0:
-            self._logger.error("stress tool binary '%s' is not available", stress_config['tool'])
+        if subprocess.call("which {}".format(self._process_args['name']),
+                           shell=True) > 0:
+            self._logger.error("stress tool binary '%s' is not available",
+                               self._process_args['name'])
             return
 
         # calculate requested load details and load split among different