get_array_inside_type added this closes #5 issue

[minven]

Now array inside pattern can be extracted using regex

➜  markdown-frames git:(regex_for_array_type_extraction) py.test tests
============================= test session starts ==============================
platform linux -- Python 3.5.1, pytest-2.8.5, py-1.4.31, pluggy-0.3.1
rootdir: /mnt/c/Users/Mindaugas/Desktop/markdown-frames, inifile:
collected 13 items

tests/test_pandas_dataframe.py .
tests/test_spark_dataframes.py ......
tests/test_utils.py ......

========================== 13 passed in 23.67 seconds ==========================
➜  markdown-frames git:(regex_for_array_type_extraction)

[Va1da2]

Good direction, although I think we should go either all the way or not at all (at least for now I see it this way). I think we can make this a general case and replace all the checks in the _types_mapping regular expression based. Maybe even in a nice, functional manner? ;)