1) Backport `path_find`
2) Disable debuginfo in RPM
3) Disable failing part of BSDSocket test

* Move building of modules into Lua (in rpmspec)
* Remove tarantool.cfg and init.d/tarantool_box from SCL spec (bug in cmake28-epel-6-x86_64)
* Merge two specs (for EL and other RPM linuxes)
* Add Fedora's Mock specifications

  * extra/rpm/tarantool-scl.rpm.spec - SCL spec for 1.5
  * extra/rpm/tarantool-el.rpm.spec.in - Enetrprise Linux 5/6 Specification
  * extra/rpm/tarantool.rpm.spec.in - Specification for other Linuxs
- Build (tarantool-el.rpm.spec and tarantool.rpm.spec) with `--define 'scl 15'`for SCL build.
- Preserve old spec (for compatibility)
- Add dependencies into Specifications, two specs for Mock.
- Create configuration files for Mock builds for EL-{5,6}-{i386,x86_64}

  Working with Mock:
    cmake .
    make new_rpm{_el,}_src
    mock -r <config> --init
    mock -r <config> --rebuild <path_to_srpm>

  Merging commits

+ fix socket:readline regexp.

+ fix bsdsocket test

 * Move source files to appropriate location
 * Remove C wrapper for isysconnect/sysbind/sendto and
 * other functions
 * Remove box.socket.errno()
 * Change sockets to be non-blocked by
 * default
 * Code style fixes
 * Other minor changes

purpose: OOS-build tests fail

 * Install *.lua modules into ${DATADIR}/tarantool/1.5
    and *.so modules into ${LIBDIR}/tarantool/1.5
 * Fix default package.path and package.cpath
 * Install Lua headers to ${INCLUDE_DIR}/tarantool/1.5
 * Install config.h to ${INCLUDE_DIR}/tarantool/1.5
 * Add a new package - tarantool-dev (server development headers)
 * Use RPM Macroses in rpm.spec
 * Fix tarball generation for Debian
 * Use GNUInstallDirs.cmake to setup directories

 + memory leak in box.net.box (timeouted responses)
 + remote:ping() never throw exception

Closes #161

move module related tests from test/box/ to test/module/.

Summary:
* PLUGIN_DIR -> MODULE_DIR
* MODULE_DIR prefix is /usr/lib/tarantool/VERSION
* MODULE_DIR automatically appends to both lua c/path
* removed plugin autoload facility in src/lua/init.cc
* removed admin console plugin dependencies
* moved src/box/lua/sql.lua to separate module = require('box.net.sql')
* moved src/plugin/pg = require('box.net.pg')
* moved src/plugin/mysql = require('box.net.mysql')
* default .so and .lua install is lib/tarantool/modules/{box/net/}
* debian spec and tests are updated

Remove fiob_open_flags, use "mode" consistently.

Rationale:
Any error which implies a system administrator action needs to be
marked explicitly in the log, so that it's easy to find and act
upon.

This change the number of log levels, so the default log level was
bumped from 4 to 5. Installations which set the log level
explicitly need to adjust their setting.

+ use luaL_ref/luaL_unref to store lua scalar instead lua metatable.
+ add :is_closed method.