Major changes and bug fixing

[ypriverol]

This PR changes the following issues:

• Search on OLS recursively when the given terms is found more than once. #160
• Increase the OLS search terms (rows) for a given query. #160
• Check empty cells in the SDRF and print the row index and the column name #153
• Small bug fixed #121

[ypriverol]

@timosachsenberg @jpfeuffer @MaLLLiYA can you review this PR.