server (install): force version of txJSON-RPC to 0.3.1: later version are bugged (unicode is badly handled). We only use if for Libervia legacy (i.e. Pyjamas version), and we'll get rid of it for SàT 0.8, so it's not a big deal to use an older version. In addition, txJSON-RPC doesn't seem maintained anymore.

try:
    from common.constants import Const as C
except ImportError:
    pass # import doesn't work at this stage with pyjamas
else:
    __version__ = C.APP_VERSION