Fix bugs (minor typos)

Fix bugs (minor typos)

Prior to this merge:

 - Incorrect UUID was being stored in completed list.
 - `save_text` was being called in the `save_plot` 0MQ API method.

As of this commit, both of these issues are fixed.

See merge request !7

Separated plot save dialogue from actual saving.

See #18

# Conflicts:
#	dstat_interface/interface/save.py
#	dstat_interface/main.py
#	dstat_interface/params.py

	- Implemented easy parameter fetching and writing.
	- Updated rest of code to reflect new access syntax
	- Moved parameter sanity checks to separate file