Adjusted gitignore

Body:
- adjusted gitignore for IDE related folders
- removed preprocessed data from gitignore

.gitignore

@@ -7,7 +7,6 @@
 /01_project_management/outlets/
 /01_project_management/rdm/
 /01_project_management/zz_misc
-/03_data/04_preprocessed_data/
 /04_analysis/
 /05_figures/
 /06_dissemination/
@@ -26,3 +25,5 @@
 *.sav
 *.html
 
+# IDE related files and folders
+.idea