[TASK] Add gitignore file and remove .idea folder

.gitignore

+#
+# Global Git ignore file
+# inspired by the TYPO3 Project
+#
+# ignoring temporary/backup files (left by e.g. vim)
+# ignoring common IDE's config directories/files
+# ignoring thumbnail db files
+#
+# for local exclude patterns please edit .git/info/exclude
+#
+*~
+*.bak
+*.idea
+*.project
+Thumbs.db
+desktop.ini

.idea/t3o_slack.iml

-<?xml version="1.0" encoding="UTF-8"?>
-<module type="WEB_MODULE" version="4">
-  <component name="NewModuleRootManager">
-    <content url="file://$MODULE_DIR$" />
-    <orderEntry type="inheritedJdk" />
-    <orderEntry type="sourceFolder" forTests="false" />
-  </component>
-</module>
\ No newline at end of file