WebSearch: partial SRU protocol support

* Implements partial support to SRU protocol as described in
  <http://www.loc.gov/standards/sru/index.html>.
  (addresses #1153)

* Operations Search/Retrieve and Explain are supported but operation
  Scan and CQL language are not supported.

* Example URL: /sru?operation=searchRetrieve&version=1.2&query=Model

Signed-off-by: Vangelis Banos <vbanos@gmail.com>
4: I102 copyright year is outdated, expected 2014 but got 2012
34: D209 Put multi-line docstring closing quotes on separate line
34: D203 Expected 1 blank line *before* class docstring, found 0
34: D204 Expected 1 blank line *after* class docstring, found 0
34: D400 First line should end with '.', not 'e'
34: D205 Blank line missing between one-line summary and description
38:5: E301 expected 1 blank line, found 0
38: D102 Docstring missing
50:23: E127 continuation line over-indented for visual indent
64:1: E302 expected 2 blank lines, found 1
64: D209 Put multi-line docstring closing quotes on separate line
64: D203 Expected 1 blank line *before* class docstring, found 0
64: D204 Expected 1 blank line *after* class docstring, found 0
64: D400 First line should end with '.', not 'f'
64: D205 Blank line missing between one-line summary and description
68:5: E301 expected 1 blank line, found 0
68: D102 Docstring missing
80:23: E127 continuation line over-indented for visual indent
110:35: F821 undefined name 'WebInterfaceDumpPages'
228:10: E126 continuation line over-indented for hanging indent
241:10: E126 continuation line over-indented for hanging indent
248:10: E126 continuation line over-indented for hanging indent
255:10: E126 continuation line over-indented for hanging indent
274:10: E126 continuation line over-indented for hanging indent
281:10: E126 continuation line over-indented for hanging indent
331:1: E302 expected 2 blank lines, found 1
331: D203 Expected 1 blank line *before* class docstring, found 0
331: D204 Expected 1 blank line *after* class docstring, found 0
334:5: E301 expected 1 blank line, found 0
334: D102 Docstring missing
340:1: E302 expected 2 blank lines, found 1
340: D290 White spaces around docstring should be trimmed.
340: D209 Put multi-line docstring closing quotes on separate line
340: D203 Expected 1 blank line *before* class docstring, found 0
340: D400 First line should end with '.', not 'l'
340: D205 Blank line missing between one-line summary and description
345:16: E127 continuation line over-indented for visual indent
381: D102 Docstring missing