NUTCH-2886 Move Nutch WebApp to separate repository

[lewismc]

This PR addresses https://issues.apache.org/jira/browse/NUTCH-2886
N.B. The code is NOT being entirely deleted... it has just been moved to https://github.com/apache/nutch-webapp such that it can be maintained as a separate layer.
This has the benefit of reducing the number of dependencies in ivy/ivy.xml and hence making the core Nutch codebase more secure especially given the low development on the WebApp.
Comments welcome. Thanks

[lewismc]

This would have the following impact on the nutch source
before restructuring

github.com/AlDanial/cloc v 1.88  T=2.42 s (415.1 files/s, 57736.9 lines/s)
--------------------------------------------------------------------------------
Language                      files          blank        comment           code
--------------------------------------------------------------------------------
Java                            658          12390          26610          60066
XML                             169           2535           3463          14813
HTML                             28           2556            376           3752
XSLT                              9            343            188           3292
Ant                              80            550           1399           1969
JSON                              2             26              0           1733
Markdown                         16            244              0            652
Bourne Shell                     28            147             99            553
Bourne Again Shell                3             78            165            549
XSD                               3             18             50            295
DOS Batch                         1             45              1            194
CSS                               1             18             25            106
DTD                               2             42            138             38
YAML                              2              6             16             35
JavaScript                        1              3              1             20
Dockerfile                        1              6             17             14
--------------------------------------------------------------------------------
SUM:                           1004          19007          32548          88081
--------------------------------------------------------------------------------

after

github.com/AlDanial/cloc v 1.88  T=2.64 s (355.9 files/s, 51112.2 lines/s)
--------------------------------------------------------------------------------
Language                      files          blank        comment           code
--------------------------------------------------------------------------------
Java                            606          11802          25691          57837
XML                             169           2532           3463          14800
XSLT                              9            343            188           3292
HTML                             18           2533            300           3249
Ant                              80            550           1399           1969
JSON                              2             26              0           1733
Markdown                         16            244              0            652
Bourne Shell                     28            147             99            553
Bourne Again Shell                3             78            165            546
XSD                               3             18             50            295
DOS Batch                         1             45              1            194
DTD                               2             42            138             38
YAML                              2              6             16             35
JavaScript                        1              3              1             20
Dockerfile                        1              6             17             14
--------------------------------------------------------------------------------
SUM:                            941          18375          31528          85227
--------------------------------------------------------------------------------

~2750 lines of code contained within the Web Application.

[sebastian-nagel]

+1 looks good, compiles, makes the Nutch job file 18 MB smaller.

[lewismc]

Thanks @sebastian-nagel