Add -a <action> parameter to JavaSearch and JavaSearchContext

The parameter allows to specify where the search result should be
opened, e.g. vsplit would open the result in a vertical split. If the
action parameter is not specified it defaults to g:EclimJavaSearchSingleResult,
which itself defaults to g:EclimDefaultFileOpenAction.

This parameter works for the JavaSearch and JavaSearchContext commands
and in the case of JavaSearchContext it is the only parameter.

Examples:
Open single search result for 'Foo' in a vertical split:
  JavaSearch -p Foo -a vsplit
Open single search result for 'Foo' in the current window:
  JavaSearch -p Foo -a edit
Ensure that -a <action> is the only parameter of JavaSearchContext

All other parameters that are passed to JavaSearchContext are removed
and -a <action> is the only one that passes through the filter.
Factor out the single result action parsing to eclim#util

By doing so it should be easier to support the -a <action> flag in
eclim's other *Search commands as well.

The two new functions in eclim#util are
  eclim#util#GetSingleResultAction(argline, default)
  eclim#util#RemoveSingleResultActionFromArguments(argline)
Add -a <action> to the command completion for JavaSearch
Add -a <action> to the command completion for JavaSearchContext
Ignore -a <action> in command completion for JavaDocSearch
Merge remote-tracking branch 'k13n/searchaction' into searchaction
attempt to simplify new -a arg support for java search commands

refs #287
add -a arg to other lang searches

- add eclim#util#CommandCompleteOptions to reduce code duplication

refs #287