Enable custom filename when downloading about scidownl

[khanfarhan10]

@Tishacy please look into this issue!

[khanfarhan10]

Also returning the saved_filepath instead of None makes more sense while downloading the files

from scidownl.scihub import *

DOI = "10.1021/ol9910114"
out = 'paper'
sci = SciHub(DOI, out).download(choose_scihub_url_index=3)

[fridrichmrtn]

You can just use this hotfix>

from scidownl.scihub import *
class SciHub(SciHub):
    def __init__(self, doi, out='.', title=None):
        self.doi = doi
        self.out = out
        self.title = title
        self.sess = requests.Session()
        self.check_out_path()
        self.read_available_links()

    def find_pdf_in_html(self, html):
        pdf = {}
        soup = BeautifulSoup(html, 'html.parser') 
        pdf_url = soup.find('embed', {'id': 'pdf'}).attrs['src'].split('#')[0]
        pdf['pdf_url'] = pdf_url.replace('https', 'http') if 'http' in pdf_url else 'http:' + pdf_url
        #title = ' '.join(self._trim(soup.title.text.split('|')[1]).split('/')).split('.')[0]
        #title = title if title else pdf['pdf_url'].split('/')[-1].split('.pdf')[0]
        self.title = self.title if self.title else pdf['pdf_url'].split('/')[-1].split('.pdf')[0]
        pdf['title'] = self.check_title(self.title)
        print(STD_INFO + colored('PDF url', attrs=['bold']) + " -> \n\t%s" %(pdf['pdf_url']))
        print(STD_INFO + colored('Article title', attrs=['bold']) + " -> \n\t%s" %(pdf['title']))
        return pdf

Also fixed in this PR #16.