Implement request_parser for parsing requests
Rename unregister_type to unregister_ops
Rename get_operation_entry() to get_op_entry()
filesystem: remove unneeded template of ctor
ops_type_db: throw an exception in get_ops()
default_file_op: read: Fix bug causing SEGV

 In default_file_op::read(), if `offset` value is
larger than file size, then out of bounds of read is occurred.
 Fix this by returning 0 if `offset` is larger than file size.
Implement chmod functionality
st_inode: return const reference to a time
Add chown support
Separate ops_type_db from fs_core.{cpp,hpp}
Implement initial poll functionality

To implement it:
 * Integrate planet::{read,write,close} into fs_core
 * Introduce new polling class, fuse_poller
Note:
 Only tcp.client_op supports this now
utils: raii_wrapper: remove `inline`
eth: raw_op: add support for poll
Remove operation_layer
Add an example using poll functionality
module_loader: don't insert '\0' into each module info
Update inode times on entry operations
tcp: data: support poll
Merge branch 'for_poll' into develop

This merge includes:
 * Implement initial poll support
 * tcp.data, tcp.client and eth.raw now supports poll
 * Access time updating
Merge branch 'develop'

Notable new features:
 * Add initial poll support
 * Add request parser