Get rid of direct org.jruby.embed.ScriptingContainer use

[dmikurube]

The Embulk core is going to make JRuby optional in next major versions (expected to be v0.10). Then, org.jruby.embed.ScriptingContainer will be no longer available.

embulk-output-dynamodb/src/main/java/org/embulk/output/dynamodb/DynamodbUtils.java

Lines 327 to 332 in fbd069f

	// Parse like "table_%Y_%m"(include pattern or not) format using Java is difficult. So use jRuby.
	public String generateTableName(String tableName)
	{
	ScriptingContainer jruby = new ScriptingContainer();
	return jruby.runScriptlet("Time.now.strftime('" + tableName + "')").toString();
	}

We'll need to consider an alternative against this...