--pwd-from-stdin now can read from STDIN.

You can use pipe to provide multiple line password.
Side effect: you can use trocla to store/retreive any kind of data,
for example, public SSH key for your deployment tool.

The former way of --pwd-from-stdin should be provided by the
option --password / -p. STDIN has a different mean, IMHO.
improve README, get rid off obsolete --pwd-from-stdin
check if format is valid before creating/seting/...

as the old code only checks if the format name is empty, we can set any
kind of key/value in the database. for example, this command will work
without any error reported:

    trocla set someuser strange_format

I replace the method miss_format by check_format that should be invoked
before any thing related to format.
rearrange format checking