Cleanup to match best practices in ruby and shell

Cleanup both ruby and shell scripts to match various linters'
suggestions. Mostly using the new hash syntax, as well as small
readability changes. Additionally, update gitignore to not accidentally
add in the output from running `rake vendor`

Author: teancom

.gitignore

@@ -4,3 +4,6 @@ Gemfile.bak
 .bundle
 vendor
 .idea
+lib/logstash-input-http_jars.rb
+build/
+.gradle/

ci/build.sh

@@ -7,15 +7,15 @@
 ########################################################
 set -e
 
-echo "Starting build process in: `pwd`"
+echo "Starting build process in: $(pwd)"
 source ./ci/setup.sh
 
 if [[ -f "ci/run.sh" ]]; then
-    echo "Running custom build script in: `pwd`/ci/run.sh"
-    source ./ci/run.sh
+  echo "Running custom build script in: $(pwd)/ci/run.sh"
+  source ./ci/run.sh
 else
-    echo "Running default build scripts in: `pwd`/ci/build.sh"
-    bundle install
-    bundle exec rake vendor
-    bundle exec rspec spec
+  echo "Running default build scripts in: $(pwd)/ci/build.sh"
+  bundle install
+  bundle exec rake vendor
+  bundle exec rspec spec
 fi

ci/setup.sh

@@ -8,18 +8,18 @@
 set -e
 if [ "$LOGSTASH_BRANCH" ]; then
     echo "Building plugin using Logstash source"
-    BASE_DIR=`pwd`
+    BASE_DIR=$(pwd)
     echo "Checking out branch: $LOGSTASH_BRANCH"
-    git clone -b $LOGSTASH_BRANCH https://github.com/elastic/logstash.git ../../logstash --depth 1
+    git clone -b "$LOGSTASH_BRANCH" https://github.com/elastic/logstash.git ../../logstash --depth 1
     printf "Checked out Logstash revision: %s\n" "$(git -C ../../logstash rev-parse HEAD)"
     cd ../../logstash
     echo "Building plugins with Logstash version:"
     cat versions.yml
     echo "---"
     # We need to build the jars for that specific version
-    echo "Running gradle assemble in: `pwd`"
+    echo "Running gradle assemble in: $(pwd)"
     ./gradlew assemble
-    cd $BASE_DIR
+    cd "$BASE_DIR"
     export LOGSTASH_SOURCE=1
 else
     echo "Building plugin using released gems on rubygems"