Addresses 22 not giving warning about incorrectly configured statements

Author: theangryangel

README.md

@@ -17,14 +17,17 @@ particular location. Please ensure you read the 4 installation lines below.
   - Altered exception handling to now count sequential flushes with exceptions thrown in 0.2.0 
 
 ## Versions
+Released versions are are tagged as of v0.2.1, and available via rubygems.
+
+For development:
   - See master branch for logstash v2+
   - See v1.5 branch for logstash v1.5 
   - See v1.4 branch for logstash 1.4
 
 ## Installation
   - Run `bin/plugin install logstash-output-jdbc` in your logstash installation directory
   - Now either:
-    - Use driver_class in your configuraton to specify a path to your jar file
+    - Use driver_path in your configuraton to specify a path to your jar file
   - Or:
     - Create the directory vendor/jar/jdbc in your logstash installation (`mkdir -p vendor/jar/jdbc/`)
     - Add JDBC jar files to vendor/jar/jdbc in your logstash installation

lib/logstash/outputs/jdbc.rb

@@ -102,6 +102,14 @@ def register
       @logger.warn("JDBC - Flush size is set to > 1000")
     end
 
+    if @statement.length < 1
+      @logger.error("JDBC - No statement provided. Configuration error.")
+    end
+
+    if (!@unsafe_statement and @statement.length < 2) 
+      @logger.error("JDBC - Statement has no parameters. No events will be inserted into SQL as you're not passing any event data. Likely configuration error.")
+    end
+    
     buffer_initialize(
       :max_items => @flush_size,
       :max_interval => @idle_flush_time,