Merge pull request #36 from rkawauchi/master

add R files
Delete the database if we are reimporting data from scratch
allow tracking whether a person has been treated
track whether each patient has been treated
Correctly return whether a treatment was performed
Fixed avg() bug returning only ints
report averages only among treated patients
Clearer output wording
Stupid weighting of health problem probability by age
Don't error out if database file doesn't exist
Run test repeatedly
Silence printed warning - unnecessary
Return qaly improvement
Plot qaly improvement
ignore .pkl files (Python storage)
Save qaly_improvement to file so it can be used later
No longer recreate database every trial
Save qaly_improvement as CSV instead
Ignore the qaly_improvement.csv
Write qaly_improvement at each iteration so never lose work