Embed folder or .fastq name as part of Firestore document name

[Firedrops]

Would aid with identifying runs. For example,

a AB_CDE.fastq will generate something like AB_CDE-2019-02-26T12-34-56UTC, instead of or in addition to resultDocument....

and a folder upload with multiple .fastq, if it's possible to detect this, be named with the folder's name.

Maybe the timestamp can be less verbose if we use the input names as identifiers.

This would also help with generating more intuitive URLs in #57.

[pseveryn]

Added in #96 . Now we have functionality of grouping results by source folder of GCS bucket.
For example, if you add next fastq files

gs://test_bucket/folder_1/1.fastq
gs://test_bucket/folder_1/2.fastq
gs://test_bucket/folder_2/3.fastq
gs://test_bucket/folder_2/4.fastq

you will have two result documents, for folder_1 and folder_2