query_classifier: implemented skygw_get_canonical which returns a copy of original string with given substrings being replaced with questionmarks.
skygw_utils.cc: added string replacement function for use of skygw_get_canonical
Completed skygw_get_canonical by adding NULL checks and debug assertions. Replacable literal types are now INT_ITEM, STRING_ITEM, DECIMAL_ITEM, REAL_ITEM, VARBIN_ITEM  and NULL_ITEM.
Test use for cacnonical query function. Effective in debug build only.
Fix to bug #479, http://bugs.skysql.com/show_bug.cgi?id=479
service.c was counting unfound filters towards the filter chain size.
Merge pull request #29 from skysql/null_filter_fix

Fix to bug #479, http://bugs.skysql.com/show_bug.cgi?id=479
Changes related to canonical query format implementation.
query_classifier.cc: Now query can be parsed outside query_classifier_get_type by calling function parse_query. It creates parsing_info_t struct which is then added to the GWBUF which also includes the query. Parsing information follows the buffered query and it is freed at the same time with query buffer, in gwbuf_free.
buffer.c: additions of parsing information to gwbuf struct.
modutil.c: added function which returns query from GWBUF in plain text string.
readwritesplit.c:routeQuery now only calls query_classifier_get_type to get the query type instead of extracting plain text query from the GWBUF buffer.
Merge branch 'MAX-160' of https://github.com/skysql/MaxScale into MAX-160
query_classifier.cc: query_is_parsed is now global function and can be used to check whether parsing information already exists in the buffer.
skygw_utils.cc: removed replace_str and implemented replace_literal which replaces user-provided literals in query with predefined string "?". Replacing is done one by one, so it is suboptimal ipmlementation since all literals could be passed to replacement function in one call and processed all before returning.
Fixed comment.
query_classifier.cc: cleaned up and simplified skygw_get_canonical
skygw_util.cc:fixed memory allocation issue where terminating byte wasn't counted. Added some error checks.
skygw_get_canonical didn't return NULL pointerin cases where parsing info didn't exist or something went wrong.
query_classifier.cc:skygw_get_canonical: if the item to be replaced is an empty string "", it is processed differently from the other cases due to difficulties to get wanted result by adding special rule for that to regex.
query_classifier.h: added parsing information structure to query classifier away from buffer.h.
buffer.c:introduced a buffer object which includes object pointer and a clean-up call-back function. Buffer objects form a list which is cleaned up by the last referrer of the buffer, as a part of gwbuf_free. Buffer object list is protected by a spinlock gwbuf_lock.
	Also added identifier type, bufobj_id_t which is enumerated type and currently includes one value only, GWBUF_PARSING_INFO. Added also a bitfield for information about the buffer. It currently has one type only, GWBUF_INFO_PARSED indicating that buffer content is parsed and there is buffer object of type GWBUF_PARSING_INFO.
skygw_utils.cc:replace_literal:changed regexec matching to case insensitive because user-defined literals are sometimes converted to upper-case ones.
canonical query tests for query classifier
the errmsg.sys file is now copied during test building
Merge pull request #30 from skysql/canonical_query_tests

Canonical query tests
more test cases for canonical queries and makefile typo fixes
query_classifier.cc:parsing_info_done: calling mysql_thread_end caused segfauls when same thread tried next time call free_embedded_thd because thread's sysvar was set to NULL in mysql_thread_end.
Added a few lines to canonical query test's input script which are not handled correctly.
Merge branch 'MAX-160' of https://github.com/skysql/MaxScale into MAX-160

Conflicts:
	query_classifier/test/canonical_tests/input.sql
skygw_utils.cc:replace_literal: Fixed regular expression which, for example,  accepted "200" with needle "2"
query_classifier.cc: fixed invalid argument list in logging command.
input.sql: added a few previously failed cases for canonical query test
Added expected results for missing queries.