detect un-decrypted env files

[tylergannon]

If one runs syk up while the environment files are still in their decrypted state, the result is a somewhat cryptic failure from docker-compose.

❯ syk up
Traceback (most recent call last):
  File "docker-compose", line 3, in <module>
  File "compose/cli/main.py", line 67, in main
  File "compose/cli/main.py", line 123, in perform_command
  File "compose/cli/command.py", line 69, in project_from_options
  File "compose/cli/command.py", line 127, in get_project
  File "compose/config/config.py", line 406, in load
  File "compose/config/config.py", line 520, in load_services
  File "compose/config/config.py", line 501, in build_services
  File "compose/config/config.py", line 501, in <listcomp>
  File "compose/config/config.py", line 493, in build_service
  File "compose/config/config.py", line 910, in finalize_service
  File "compose/config/config.py", line 695, in resolve_environment
  File "compose/config/environment.py", line 38, in env_vars_from_file
  File "site-packages/dotenv/main.py", line 318, in dotenv_values
  File "site-packages/dotenv/main.py", line 86, in dict
  File "site-packages/dotenv/main.py", line 93, in parse
  File "site-packages/dotenv/main.py", line 48, in with_warn_for_invalid_lines
  File "site-packages/dotenv/parser.py", line 235, in parse_stream
  File "site-packages/dotenv/parser.py", line 107, in __init__
  File "/Users/administrator/jenkins/workspace/dsg_compose_1.27.4/venv/lib/python3.7/codecs.py", line 322, in decode
  File "/Users/administrator/jenkins/workspace/dsg_compose_1.27.4/venv/lib/python3.7/encodings/utf_8_sig.py", line 69, in _buffer_decode
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe8 in position 13: invalid continuation byte
[28536] Failed to execute script docker-compose

We could either check the .env files to ensure they are plain text before calling docker-compose, or else catch a CalledProcessError that encapsulates the UnicodeDecodeError raised by dotenv when it tries to open the encrypted file.

[Didericis]

This issue completely went under my radar... is a good suggestion/we should probably add this