[lib] cleanup some compiler warnings

   - lib/searpc-client.c:353:1: warning: control reaches end of non-void function [-Wreturn-type]
   - lib/searpc-utils.c:93:13: warning: enumeration value 'JSON_ARRAY' not handled in switch [-Wswitch]
[tests] using clar now

  - enable test in travis-ci script
[build] Add CMake Build System

  - clar patch for cmake