* Add checks for additional reserved ip addresses

100.64.0.0/10 and 240.0.0.0/4 are both reserved but not currently
filtered.

* Add check for special purpose addresses

192.0.0.0/24 - Used for the IANA IPv4 Special Purpose Address Registry

* Refactor ip_utils (#5872)

* Add checks for all ipv4 special use addresses
* Add comprehensive ipv4 test cases

* Refactor Ipv6 address checks (#5872)

* Refactor AllowIP (#5872)

* Add IpFilter struct to wrap predefined filter (AllowIP) with custom
allow/block filters.
* Refactor parsing of --allow-ips to handle custom filters.
* Move AllowIP/IpFilter from ethsync to ethcore-network where they
are used.

* Revert Cargo.lock

* Tests for custom ip filters (#5872)

* Add "none" as a valid argument for --allow-ips to allow narrow
custom ranges, eg.: --allow-ips="none 10.0.0.0/8"
* Add tests for parsing filter arguments and node endpoints.
* Add ipnetwork crate to dev dependencies for testing.

* Add ipv6 filter tests (#5872)

* Revert parity-ui-precompiled to master

* Fix minor detail in usage.txt (#5872)

* Spaces to tabs

* Rename IpFilter::new() to ::default()

* Small readability improvements

* Test (#5872)

* Revert "Test (#5872)"

This reverts commit 7a8906430a6dad633fe29df3dca57f1630851fa9.