Results: Default latency-histrogram with Spirent TestCenter

Results: Default latency-histrogram with Spirent TestCenter

The patch adds support to provide Latency histogram from Spirent traffic
generator.
1. 03_traffic.conf: Enable histogram, and set type (default)
2. testcenter.py: If histogram enabled, call the script with right flag.
3. testcenter-rfc2544-rest.py: configure and write histogram to a
separte file in the default results folder.
4. Fix PyLint Errors
5. Adding a patch to test the 'build-error-fix'. Increased the
MAX_MEMSEG of in DPDK-config to 1024
6. Adding MAX_MEMSEG configuration at common_base didn't work.
7. Included packet sizes in the output.
8. Included description under spirent TGen
9. Removed MAX_MEMSEG configuration.

Change-Id: I7787c1768d7ac650f0ce581f17ec78df7a964e31
JIRA: VSPERF-522
Signed-off-by: Sridhar K. N. Rao <sridhar.rao@spirent.com>
(cherry picked from commit 6895bba12f952ef8925e14d404aa1ab2184ffd8f)