bug(*): fix Boolean query params

[zbjornson]

Affects plots and anything else where CellEngine's API is case-sensitive (might only be plots). We'll make the API case-insensitive at some point soon as well.

Fixes #124

[gegnew]

lgtm 🌞

[gegnew]

I guess if you wanted to be tricky I guess you could make prepare_params a decorator, which would make the implementation look like:

@prepare_params
def _get():
    # ...
    # instead of:
    # params=prepare_params(params if params else {}),

which would look like:

from functools import wraps

def prepare_params(f):
    @wraps(f)
    def wrapped(*args, **kwargs):
        if "params" in kwargs:
            kwargs["params"] = {k: str(v).lower() if type(v) == bool else v for k, v in kwargs["params"].items()}
        return f(*args, **kwargs)
    return wrapped

[zbjornson]

I like simple ;).