Requirements without specific version

[chenjr0719]

@benchuang11046 Notice that we remove all versions of requirements(here). This might cause some issues when using run_jnb because of mismatch version with nbconvert. Maybe we still need to use fixed version of all modules in both jupyter_api_default_requirements.txt and jupyter_app_default_requirements.txt. What's your thought?

[benchuang11046]

Yes, we need to fix version in both default requirements.
Here will append user requirements if the requirement not in default.
Therefore, it must be the fix version in analytics requirements.txt. Based on the jupyter_api_default_requirements.txt and jupyter_app_default_requirements.txt.
I think it's ok.

[chenjr0719]

Ok, I found I just missing some lines of code. Understand what happened about requirements in parser.py.