ncbi_blast_plus: Remove explicit shared_inputs in parallelism definitions.

Since pull request 142, these are no longer needed - anything not split is assumed to be shared.

https://bitbucket.org/galaxy/galaxy-central/pull-request/142/small-task-splitting-simpliciation/diff
ncbi_blast_plus: Use newer xml tag for defined XML macros.
ncbi_blast_plus: Refactor requirements and version tags out into shared macros.
ncbi_blast_plus: Create and utilize macro abstraction for advanced options.
ncbi_blast_plus: Reduce duplication in help sections by creating constants for references and output format descriptions.
ncbi_blast_plus: Reduce duplication in help sections by creating constants for FASTA and search time warnings.
ncbi_blast_plus: Create macros for some common parameters.

Namely parse_deflines, max_hits, and filter_queries (one variant).
ncbi_blast_plus: Reduce output handling duplication in cheetah with new @BLAST_OUTPUT@ macro.