Implementation of HTTPD protocol, gwbuf properties and a dmeo web application
interface to test the new httpd.
Merge branch 'httpd' of github.com:skysql/MaxScale into httpd
Added some documentation
Initial HINT structure added
Merge branch 'httpd' into MAX-157

Conflicts:
	server/core/buffer.c
	server/include/buffer.h
Hint parsing
Bug 462, http://bugs.skysql.com/show_bug.cgi?id=462, fixed path MAXSCALE_HOME path expression in server/test/makefile
Added check for session state before calling router->sessionClose
MAX-157. Added support for hints in rwsplit router.
buffer.c: added memory release for hint of a GWBUF
hint.c: added bool hint_exists()
hint.h: added placeholder for hint type HINT_ROUTE_TO_ALL which doesn't have implementation yet.
filter/Makefile: fixed dependency issue
hintparser.c: added const char* token_get_keyword(), hint_parser:added NULL check, hint_next_token: fixed off-by-one bug
readwritesplit.h: added bitfield for hints' use, which includes route targets and flag for case where user hinted to route to named backend server.
readwritesplit.c: added function route_target_t get_route_target() for resolving route target based on 1) query type (from query_classifier) 2) transaction state (active/not) and 3) hints. Modified get_dcb, which is called in routeQuery to provide pointer to correct backend DCB. Now get_dcb also takes server unique name as a parameter if such a hint was found. for hints' use, which includes  enter the commit message for your changes.
config.h: Added enumerated types MAX_RLAG_AVAILABLE and MAX_RLAG_UNDEFINED to be used instead of magic numbers as max_slave_replication_lag values.
readwritesplit.h: Added TARGET_RLAG_MAX to the list of hint targets. It is used in case of hint max_slave_replication_lag=<value>
readwritesplit.c: get_dcb is called when readwritesplit router chooses target backend for a query. Backend is selected from those the router has connection to. get_dcb now takes additional parameters, name and max_rlag. Name is used if there is a hint route to server <server name>. max_rlag is used for hint max_slave_replication_lag=<value> or if it doesn't exist, then for configure parameter max_slave_replication_lag=<configured value> or if both are absent, ignored.
Applying changes made in commit fa1f9ec13113e00e65f2425b080cfb0d102b0872 to this branch.
readwritesplit.c: corrected max_replication_lag with max_slave_replication_lag in hint parameter comparison functions.
Bug #468, http://bugs.skysql.com/show_bug.cgi?id=468, Query classifier accessed freed thread context. If parsing fails thd doesn't need to be freed because it holds correct information about command type.
session.c:session_setup_filters : fixed memory leak
hintparser.c: added token_free for HINT_TOKENs and fixed a few memory leaks.
mysql_client_server_protocol.h: added mysql_protocol_done which frees memory blocks pointed to by protocol members. Those can't be freed in dcb.c because dcb.c doesn't know about protocol's members.
mysql_backend.c:gw_backend_close: fixed memory leak
mysql_client.c: gw_client_close: fixed memory leak
mysql_common.c: added implementation of mysql_protocol_done
        :protocol_archive_srv_command: tried to fix memory leak. Some memory is still leaking according to valgrind. Removed use of uninitialized local variable len.
readwritesplit.c: Fix to bug #469, http://bugs.skysql.com/show_bug.cgi?id=469,  rwsplit counts every connection twice in master - counnection counts leak
	execute_sescmd_in_backend: fixed a memory leak - visible only in DEBUG=Y build.
readwritesplit/test/makefile: added target for hints tests
Merge branch 'Z2' of https://github.com/skysql/MaxScale into Z2

Conflicts:
	server/core/modutil.c