Worker commands omit target relation's schema

_From @samay-sharma on November 21, 2014 15:23_

Steps to reproduce:

``` sql
# On master and worker nodes:
CREATE SCHEMA test_schema;
# CREATE SCHEMA

# On master node:
CREATE TABLE test_schema.customer_reviews
(
customer_id INTEGER,
review_date DATE,
review_rating INTEGER,
review_votes INTEGER,
review_helpful_votes INTEGER,
product_id CHAR(10),
product_title TEXT,
product_sales_rank BIGINT,
product_group TEXT,
product_category TEXT,
product_subcategory TEXT,
similar_product_ids CHAR(10)[]
);
# CREATE TABLE

SELECT master_create_distributed_table('test_schema.customer_reviews', 'customer_id');
# master_create_distributed_table
# ---------------------------------
#
# (1 row)

INSERT INTO test_schema.customer_reviews (customer_id, review_rating) VALUES (4687, 5);
# WARNING: Bad result from ip-10-181-241-37.ec2.internal:5432
# DETAIL: Remote message: relation "customer_reviews_86" does not exist
# WARNING: Bad result from ip-10-102-169-241.ec2.internal:5432
# DETAIL: Remote message: relation "customer_reviews_86" does not exist
# ERROR: could not modify any active placements
```

Worker node log:

``` sql
# LOG: statement: INSERT INTO customer_reviews_86 (customer_id, review_rating) VALUES (4687, 5)
# ERROR: relation "customer_reviews_86" does not exist at character 13
# STATEMENT: INSERT INTO customer_reviews_86 (customer_id, review_rating) VALUES (4687, 5)
```