2.1.0

Added support for decay functions:

• DECAY_GAUSS
• DECAY_EXP
• DECAY LINEAR

Added support for vector functions

• COSINE_SIMILARITY
• L1_DISTANCE
• L2_DISTANCE

Added support for PRUNE variable

Improved the datetime saving format.
Zulu time isn't required anymore. The the given timezone is respected and saved as either Zulu or the different with GMT. (+02:00 etc)

Fixed bug in _id validation; which now allows for single character _keys as part of _id.