Split libraries fastq

Adds the StudyPreprocesser class, which allows to preprocess the raw data of a study. Currently, it only supports Illumina data, but the code should be easy to expand to support other types.

I've also modified the `insert_filepaths` function, so it now supports to pass the filepath type either by id or by the string (name).

I've modified the initialize.sql file, to support the correct filetypes for the Illumina data and its preprocessed data. I had to modify multiple files due to this change.
We don't have a default config file for Qiita? i.e. how Travis is handling all the other directories? I just did the same that is done for all the other ones. on the config_test.txt and the config_demo.txt config files it is defined to /tmp/