Install SwiftLint via the install_contributor_tools script. (#1145)

* Install SwiftLint via the install_contributor_tools script.

* Exclude catalog/third_party from SwiftLint.

* Added line length to .swiftlint.yml

* Fixed SwiftLint warnings with some minor refactors.

* Revert "Fixed SwiftLint warnings with some minor refactors."

This reverts commit 2c19802.

* Revert "Added line length to .swiftlint.yml"

This reverts commit 12a6781.

* Revert "Exclude catalog/third_party from SwiftLint."

This reverts commit 8a00ad8.

Author: ajsecord

.travis.yml

@@ -15,8 +15,7 @@ env:
     - DESTINATION="platform=iOS Simulator,name=iPhone 7,OS=10.2" SDK="iphonesimulator10.2"
 before_install:
   - gem install xcpretty --no-rdoc --no-ri --no-document --quiet
-  - brew update
-  - brew install swiftlint || true  # If already installed, don't fail.
+  - scripts/install_contributor_tools
 # The travis_wait prefix ensures that the build doesn't error out because too much time went past
 # without any output being produced.
 script: