Suite for TCPMD5 added, suite for PCEP expanded.

Suite for TCPMD5 added, suite for PCEP expanded.

The TCPMD5 suite covers entirety of
https://wiki.opendaylight.org/view/TCPMD5:Lithium_Feature_Tests#How_to_test

Notable library (Robot Resource file in fact) is introduced:
ConfigViaRestconf, which simplifies the task of overriding
config-subsystem state at runtime using restconf, at least for XML data.
Tcpmd5-specific config data is present in variables file.

Testplan is included, which in future would run
all suites needed for testing user-facing karaf features
of BGPCEP and TCPMD5 projects.

Also, clone of basicpcep is added, named pcepuser.
The reason is that the new name is more natural
for the new testplan contents, but we do not want to break
existing jobs using basicpcep suite right now.

+ Pcep variables file contains comments, helpful and structured.
+ Resource (library) for PCEP operations added.
+ The pcepuser suite now covers the entire
https://wiki.opendaylight.org/view/BGP_LS_PCEP:Lithium_Feature_Tests#How_to_test

+ pep8 compliant
+ applied: python -m robot.tidy --inplace
+ ${RESTCONFPORT} and ${NEXUSURL_PREFIX} used
- ConfigViaRestconf keywords for JSON data are not implemented at all
- Quality of tcpmd5 variables file is somewhat lacking

Change-Id: I94e77d2effef77f7bf8c23d4bc61f2ceeeb3a034
Signed-off-by: Vratko Polak <vrpolak@cisco.com>