Pyspaces

Added
- target, args, kwargs as clearly required arguments
- get, get_all functions into args_aliases.py
- processing of different types of values for uid_map and gid_map agrguments
- proc, rootdir, workdir, daemonize, stdin, stdout, stderr arguments into Container.__init__
- runup, preup, daemonize, chroot, chdir, chtty, postup, exceptup, preexec, postexec, exceptexec functions into Container
- proc variable into Clone and Container
- setns now can take path to namespaces files as arguments
- parent_pid as second argument into setns

Changed
- add rasing value error in setns
- processing of args and kwargs in Container.__init__
- Chroot class now based on Container
- change pid to target_pid first argument in setns
- set to None default values for 6 ns flags in Container.__init__ and setns
- up README and docs

Removed
- except block from setns

Fixed
- order of namespaces in args_aliases: it's important for setns! via src of nsenter
- docstrings
- readme

Added
- setns.py with setns context manager
- args_aliases.py with dicts of possible additional arguments for many cases
- Inject class and cli

Fixed
- error handling with ctypes in cloning.py
- setns

Fixed
- docstrings
- error handling
- add multilicensing: now pyspaces under MIT or BSD or Apache 2.0
- up cli and example in readme

Added
- 'all' argument into Container.__init__

Added
- link to python-nsenter in readme
- TODO into readme
- discuss and link to butter in readme
- additional argument 'all' in cli

Changed
- add alisas 'mnt' for 'fs' option of cli execute
- update importing in process.py
- docstrings
- cli structure

Fixed
- readme for pypi