Update build scripts

Update build scripts

1) Add build options to enviornment(env) to avoid export variables
2) Sync with the newest code
3) Update Readme(Readme.scons.txt)
4) Extend arduino supporting
5) Add build scripts for services
6) Add a doc(scons_script_how_to.txt) about how to write iotivity
    build script
7) change resource libs from static library to share library

Last sync and test with the newest code commit:
  e9403ce6d4d7a1a0ac8d12c5acc876af7f7a8f76

Note:
  Scripts for Service are provided but aren't enabled due to the
service code is too old it can't pass the build.

Change-Id: I06427cfe65e6fcf5837376f2f89d1e93c662f920
Signed-off-by: Caiwen Zhang<caiwen.zhang@intel.com>