Add YAML config file for WAIL preferences, paths, etc.

[machawk1]

...specifically for variables that are independent of the tools and are currently hard-coded in the Python. Suggested via @ibnesayeed.

[machawk1]

Sample WAIL Prefs options, to be read from YAML (related to this ticket and #304 and #212 .)

WAIL Preferences

Archives location ____ (browse)


Memento Aggregation

 Archives Aggregated

 id  name  timemap  timegate
 ...
 <X> include local WAIL

 For each archive...(minutes+seconds, e.g. 1m5s)
 >   Response Timeout  ___
 >     Header Timeout  ___
 > Connection Timeout  ___
 
 Aggregator Run mode
 (o) Service (x) One-off/on-demand

...to be implemented using wxPython.