Mllib perf tests added to spark-perf

MLlib performance tests added. The following algorithms have performance tests now:
 - Regression and Classification:
1) Linear Regression
2) Lasso
3) Ridge Regression
4) Logistic Regression
5) SVM
6) Naive Bayes
7) Decision Trees
 - Optimization
8) L-BFGS
 - Clustering
9) KMeans
 - Recommendation
10) ALS
 - Linear Algebra
11) SVD
12) PCA
13) Multivariate Statistics Calculation
 - Statistics Toolbox
14) Pearson Correlation
15) Spearman Correlation

Additional functions added to bin/run and config/config.py.template to host these tests.
Looks like you duplicated `run_python_tests` when cleaning up the merge conflict.  I'll fix this.